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I optimized the structure of Pd Acetate Trimer using HF/STO-3G and the B3LYP/LANL2DZ without any solvent. The optimization was successful without any negative frequency.
Then I added solvent IEFPCM/DCE to the system. This causes the optimization to show error link 9999. How Do I fix this problem ?
I have tried using the last optimized geometry and used that for next calculation but every time its showing same error.
I am adding the drive links to the files herewith:
It has the input geometries and log files for both without solvent and with solvent calculations.
Can anyone please help ?
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n is time. and i want to know if the distribution of small scale fading is correct or not.
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Thank you Miang Hong Ngerng. No problem but your mistake is on line 7 of page 1. The sum of two correlated normal variables is not normal, in general. Except if the two variables are suppose to be distributed according to a bivariate normal distribution. See, e.g., https://planetmath.org/sumsofnormalrandomvariablesneednotbenormal and https://math.stackexchange.com/questions/4274029/sum-of-normal-random-variables-being-not-normal for a good counter-example.
You mention AR(1) models. The arguments above apply to forecast intervals. If the process is Gaussian (implying that every subset of the variables has a multivariate normal distribution), then you can obtain forecast intervals by using your arguments. Otherwise, you can write the mean and the variances of your forecasts but not obtain forecast intervals. I hope this is clearer.
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Full Paper
Abstract
Three recent breakthroughs due to AI in arts and science serve as motivation: An award winning digital image, protein folding, fast matrix multiplication. Many recent developments in artificial neural networks, particularly deep learning (DL), applied and relevant to computational mechanics (solid, fluids, finite-element technology) are reviewed in detail. Both hybrid and pure machine learning (ML) methods are discussed. Hybrid methods combine traditional PDE discretizations with ML methods either (1) to help model complex nonlinear constitutive relations, (2) to nonlinearly reduce the model order for efficient simulation (turbulence), or (3) to accelerate the simulation by predicting certain components in the traditional integration methods. Here, methods (1) and (2) relied on Long-Short-Term Memory (LSTM) architecture, with method (3) relying on convolutional neural networks.. Pure ML methods to solve (nonlinear) PDEs are represented by Physics-Informed Neural network (PINN) methods, which could be combined with attention mechanism to address discontinuous solutions. Both LSTM and attention architectures, together with modern and generalized classic optimizers to include stochasticity for DL networks, are extensively reviewed. Kernel machines, including Gaussian processes, are provided to sufficient depth for more advanced works such as shallow networks with infinite width. Not only addressing experts, readers are assumed familiar with computational mechanics, but not with DL, whose concepts and applications are built up from the basics, aiming at bringing first-time learners quickly to the forefront of research. History and limitations of AI are recounted and discussed, with particular attention at pointing out misstatements or misconceptions of the classics, even in well-known references. Positioning and pointing control of a large-deformable beam is given as an example.
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Dear
I'm really thankful to all of you for your precious time and valuable comments.
Regards,
Elaine Lu
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Hello, I'm a very new user of Gaussian 16. So, I started doing optimization and frequency of MIL-53(Fe) [construct with 3 atoms Fe and 4 bdc linker] cluster model using MN15L/genecp. The calculation was finished and I got inp.log. How do I know is the optimization and frequency calculation was success? And how do I get these data: (1) The optimized structure, (2) Thermodynamics (like enthalpy, Gibbs free energy, etc).
Please, advise me.
Thank you.
R. S.
This is my input
%mem=32Gb
%nproc=12
#p MN15L/genecp opt freq=NoRaman
test
-1 2
.....
****
O 0
6-31+G(d)
****
C H 0
6-31G(d)
****
Fe (lanl2ldz)
****
FE
FE-ECP (lanl2dz)
****
Note: Actually I wanna calculate the energy adsorption of CO2 using the energy that I got after opt and freq calculation with this formula: Eads= Esystem - (EMOFs + ECO2).
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Hi,
You can find all the related information in the log file.
In a successful optimization the following command will print the line:
grep "Otimization completed" log-file
If the optimized structure is a stationary one, then the following command will print that information:
grep "Stationary point found" log-file
After the frequency calculation the thermodynamic data is printed in the log file following the "Thermochemistry" line. Search for "Zero-point correction".
To get the optimized structure, you can use GAUSSIAN newzmat command:
newzmat -ichk -opdb -N 9999 chk-file out-file
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Can we do the computational studies of ZnO Nanoparticles using Gaussian Software? If yes, Which structure of ZnO can we use to compare Theoretical work with experimental work?
#computationalstudies #ZnO #ZnOnanoparticles #nanoparticles #Gaussiansoftware #ZnOstructure #theoreticalstudy
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When comparing theoretical work with experimental work for ZnO nanoparticles, it is common to use the wurtzite crystal structure. It is a hexagonal structure with alternating layers of zinc and oxygen atoms.
Keep in mind that when working with nanoparticles, the size and shape of the nanoparticles can also influence their properties.
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The code should be well documented with examples.
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Sigfried Vanaverbeke You might look for libraries or code snippets with decent documentation and examples and determine whether they fit your requirements. Check to see if the code has been tested and confirmed by the community as well.
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Hello everyone,
I am currently trying to run an IRC calculation for a RO2 structure isomerizing to the QOOH structure for the Ethanal +OH system. The RO2 and QOOH energies are agreeable with literature and the TS that was found seems to have the right imaginary frequency and movement, and it has an energy that is closer to the literature values. But whenever I run an IRC calculation, I see on GaussView that the hydrogen abstraction stops halfway and then goes back to the RO2 without ever forming a bond for the QOOH. I have tried reducing the step size, increasing the maxpoints, and even trying LQA. I have also tried doing separate IRC calculations for the forward and reverse reactions, to no fruition. Is this an indication that the TS is still wrong, or maybe the QOOH structure is incorrect? Or, is there a keyword in the route section that I am missing?
Please advise, thank you.
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In that case, I would say that the TS is correct, if each optimization leads to different structures. How large is the energy difference between the RO2 and QOOH structures in the IRC? If it is too large and the TS lies very close in energy to QOOH, maybe it goes back too "easily" and that's why the IRC didn't land on that structure.
Something you can do to mimic an IRC using the manual displacement approach is to repeat it, but instead of going as far as 1.00 and -1.00, go just to 0.25 and -0.25, and then use opt=(calcall,maxstep=5). By using such a small step size and calculating force constants analytically at each step, the result you would get will be very similar to that of a "true" IRC. And if you get again the same result as before (one goes to RO2, the other to QOOH), then you will have more than enough reliable evidence that the TS is correct.
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How to find out predictors' contribution in Gaussian process regression (i.e., Predictor Importance by Permutation)? Is there any example for predictors' contribution in Gaussian process regression using the sklearn package in python?
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You may use PCA and LDA based on variance. Or feature importance using different feature importance techniques. You may also try explainable artificial intelligence.
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Kindly if there is an applied example or an algorithm that explains the steps of this method
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Take a look at the attached information. It should be helpful to you. Best wishes David Booth
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I am working with electricity time-series data collected at 15 minutes intervals. I am looking for a procedure/theory to find the pattern/sequence in the time-series data based on given features. As I am working with electricity time-series data and solving the problem of solar PV identification from these data, the given features would be:
1. There is a fall in electricity consumption during 7am-8am as generation from the PV starts.
2. There is a rise in electricity consumption during 5pm-6pm as generation from the PV ends.
See the attached figure to understand the above two features.
I have gone through the literature for the same. I got the following:
  1. Gaussian prior: This works with considering the prior knowledge and evidence. In this case, the prior knowledge would be above two features, and the evidence would be the time-series data.
  2. Cross-correlation: This basically looks for the relation between two patterns.
  3. Various ML techniques: The different ML techniques can be applied such as clustering, HMM, DTW etc.
I am not looking to solve this problem with option 3. Can anyone guide me with the option 1 as it looks more relevant to my problem. I cannot understand how Gaussian prior can fit into the problem. Summarily, I want to utilize above two features as the prior knowledge and use the given data(electricity time-series) as the evidence to prove that the solar PV panel is present or not.
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I want to optimize a structure with two different material of Phosphomolybdic acid (PMA) and 4,4′-bipyridine, but I can't run out with a chk point file.
Error message always show convergence failure error termination via I502 and no lower energy was found error termination via I508
I had tried with all possible changes such as adding instruction like SCF=QC, YQC and switch to a lower basis set like HF/STO-3G and DFT-B3LYP/STO-3G, but after runing about 20 days it still didn't work.
My version is gaussian16 32 bites and gaussianview06 32 bites.
Below is my .gif input file and calculation command # opt hf/sto-3g scf=qc %mem=2000 MB
Could anyone give me some advices to figure out this question? Thanks a lot!
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Massimiliano Arca appreciate for your response.
could I attain further advises from you? Thanks!
1. what if I balance cation by setting charge to -1 or adding 2 PMA and 3 BPY into structure, it will be worked?
2. May I ask your recommendation theory for calculate HB interaction, because I am poor of acknowledge about calculate theory, thanks again.
best regards.
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I'm doing a reserch about heat and mass trasfer so, I tried to do the same research that has been by someone.
The research about vortex generator in a blocked channel for heat transfer enhancement.
The resercher used ((2D Desgin, using the hybrid genetic algorithm (GA) combining with Gaussian Process.
in Gaussian method are obtained by solving energy equation followed by the flow field using Navier–Stokes solver.
The flow is considered to be two dimensional, steady state, laminar and incompressible with constant fluid properties. Body forces and viscous dissipation are ignored. Also there is a negligible radiation heat transfer since there is no considerable temperature gradient.
The thermal properties of the fluid are assumed to be constant, and the buoyancy effects are negligible.))
I tried the same thing but the result was difference. I think I made a mistake in somewhere but I could not find it.
need some help.
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Muhammed Sipahi Analytical solutions to the Navier-Stokes equations, on the other hand, are not conceivable. As a result, it is important to simplify the equations and solve them iteratively. To mimic a gas or liquid movement in a certain environment, the user must first decide which simplifications to utilize.
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I am trying to implement the Gaussian process-based model predictive control, where the Gaussian process is used to model the unmodelled dynamics of the system. I understood the theory behind it but faced difficulty in the implementation, basically in optimising the cost function in code. Please share any reading material or tutorial code with me.
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Mohammed Yousri Silaa thank you so much for sharing the resources.
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I optimized a transition state using tight convergence criteria and all the four convergence criteria are yes; but when i run the IRC it stops after 3 or four steps ?
1-in the first attempt i added int=ultrafine
2-in the second attempt i added: LQA word, increased the stepsize from 5 to 10, and added recalc=5
Can someone help me to solve this problem?
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This is a common problem with IRC calculations. I use the following keyword:
irc=(calcall,forward,maxcycle=100, maxpoints=30,stepsize=10)
Either forward or reverse, adapting "maxpoints" and "stepsize" for your system. The option "calcall" always resulted in a Normal Termination by my side and it is surely more time consuming!
Hope this could help you!
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I would like to check the possibility of implementation of BO using C language.
The implementation target is MCU like Tricore or further.
Is this possible?
Moreover, is there anyone know where the C-implementation sources is present at github or other sites?
Finally, what would be the most difficult parts while I try to implement BO to MCU starting from matlab toolbox or python code (@github) ?
I know that BO uses Gaussian Process Regression in order to estimate surrogate function from experiment data. Is this the most difficult part for implementation of BO?
Thanks in advance.
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Dear Youngil,
I highly recommend the Matlab coder based on my experience. This package allows one to seamlessly generate C code from Matlab as long as no prohibited functions are used. I have used this to deploy code to MCUs on several occasions.
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i restarted an opt +Freq job with the keywords opt=restart, pop=nboread... but the output file do not contain any NBO section as it should ( i an need the natural population analysis) ! can i get it from the chk file? is there any othar to avoid re run the process
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First of all, do you have NBO program? is it well installed and in communication with gaussian?
It is an important check before trying to solve your problem as NBO is not free (You could have a look on Janpa Project for this purpose if you absolutely need it).
Then, I encountered recurrent problems trying to perform optimization with NBO following by "FREQ" with the following instructions: "POP=SAVENBO" or "POP=NBO6READ" (I have NBO 7.0 program). Whereas, I don't have any issues with the non-use of "FREQ" keyword.
I totally agree with Prof. Massimiliano Arca and I'm happy to know how to circumvent this problem with the given answer. Otherwise, I usually perform a OPT + FREQ calculation with Gaussian and then perform another one with POP=SAVENBO or POP=NBO6READ with the optimized geometry and "SP NOSYMM" to have a NBO analysis at the same level of theory of course.
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We know that LU decomposition is an important method for stochastic simulation of 2D RF. Assume the covariance matrix of regionalized RVs is C, it can be decomposed as C=LU according to the LU algorithm, then a RF can be generated by X=L'*y, where y is a vector consisting of independent standard normal random numbers. I want to know whether can I use LU decomposition for simulation if n observations exist as the conditioning data? If so, how can it be demonstrated?
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Thare are many decomposition types, Why you do not try another of what you applied before
regards
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While reading a research paper I have found that to find the abnormality in a signal authors were using a sliding window and in each window he was dividing the mean^2 by variance. After searching in the internet I found a term called fano factor but it was inverse of that. Could anyone please give an intuitive idea behind
the equation mean^2/variance?
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This criterion has some advantages:
It does not have unit. It is a coefficient. Therefore, you can compare different signals.
I think it stems from the coefficient of variations (CV). It is the inverse of square of CV. CV is a standardized deviation index.
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Many references are explained that kriging and GP regression is the same. However, in the formulation, they have differences from each other. Can you explain the difference between these two methods from the statistics domain?
Actually need to compare for different kriging methods, for example, simple kriging assumed that the mean of the random function is known and constant as GP regression. However ordinary kriging assumed the mean of the function is known and changing locally (E(x)).
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I hope the following article may be helpful to understand the difference(s) between Kriging and Gaussian Process regression.
Thanks!
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I want to perform a checkerboard resolution test of my tomographic inversion. What kind of function do people use to make the checkerboard model of low/high anomalies? Bell-shaped (gaussian) anomalies?
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Bruno, did you get an answer to your question. I'm interested in the answer since I'm dealing with the same issue.
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Hi, I am doing an optimisation job for the molecule, but after a long wait it comes out with operation on file out of range. The job runs just alright for another molecule in the same homologous series. Anyone knows what is going on?
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Dears
I am doing QM/MM calculations and trying to optimize a Gaussian input file of about 35000 atoms. QM region contains 60 atoms. But after a long time, I got an error that Max no. of micro-iterations restarts exceeded. Can anyone help me out?
Format of input file;
%chk=/home/SKD/work/gaussian/calculations/g23.chk
%mem=32GB
%nproc=16
#n oniom(hf/6-31g:UFF) opt=ReadFreeze scf=(xqc,maxcycle=1000)
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Yes, I did that. By incorporating the opt= quadmacro in the route section worked for me. You can also use that. If you still persist problem, please tell me then, I will be more than happy to answer you.
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That's a graph for Intensity-2Theta .
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Sadegh Mojahedfar FWHM or the integral breadth (in some cases) play a vital role in the calculation of crystallite size (through Scherrer equation), microstrain, and Williamson-Hall plot etc. In the following video tutorial, I have discussed how to calculate FWHM using Origin. For example, FWHM is used in XRD for calculating crystallite size with the help of Scherrer equation. The video explains all the steps to be performed to calculate FWHM. In the case you want to further ask about it, please do comment on the specific video, I'll respond to it shortly. I have provided the practice file here. Thanks
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Hello everyone,
I want to perform some gaussian calculations and want to use Materials studio for my research work. Can anyone guide me how to get access to supercomputer resources in India for these jobs? I am ready to pay charges for the usage.
Thank You.
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Try the High-Performance Computing Laboratory at IUAC, Delhi. The facility is for the users from universities, colleges and institutes across the country.
If you wish to use e-mail a request to sumit@iuac.res.in with a short (~ 1 page) description of the proposed work, the software you require, and the resources you need for a typical run (number of cores, amount of RAM, disk space, time).
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Greetings,
I have a bit of problem in setup the basis set of my DFT study for ZnO.. As you can see in the image attached below, I use B3LYP 6-31G (d,p) for geometrical opt. of ZnO.. But sadly, I still cannot get the energy gap of 3.4 eV for ZnO... At best I can get is 3.6 eV when using B3LYP 6-311G... Can someone make a suggestion on how to improve my calculation to get an accurate energy gap of ZnO using B3LYP.... Thank you !!
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Thank you so much dear Dr.
Driss Fadili
:)))
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I am working with the algorithm Gaussian Process Regression. I used gaussian process regression module from scikit learn library of python. But I couldn't correlate the hyperparameters of Gaussian Process Regression(GPR) implemented in sklearn with that in actual mathematical equation. So, if anyone can give any suggestion about this it will be very helpful for me. In addition to that, I am also trying to optimise the hyperparameters of GPR. If anyone can do any favour for this specially provide any codes for this I will be really grateful. Any suggestions are highly appreciated. Thanks in advance.
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Bayesian optimization
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I have done docking a ligand molecule with a receptor. After the docking, I separated the ligand from the receptor. Now I need to add partial charges to the ligand without minimizing its energy.
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Hi Susantha,
Try Open Babel. Its usage is as follows:
babel -ipdb lig.pdb -omol2 lig.mol2 --partialcharge eem
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Dear all,
I've read some literatures that say Kriging works only for single output(scalar output) .But the DACE toolbox handbook mentions that it can handle multiple response case(P15, chapter5.1).So I am puzzled . If the output is high-dimensional (hundreds of thousands), how can i deal with it? (i.e.the output of an input sample is a vector, or a curve).Especially when combined with adaptive filling criteria ,like EGO etc. ?
Many thanks!
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Donald Myers In my case,an output corresponding to each sample is a curve that changes with time or space or frequency. For example, 100 input samples(100*1) corresponding 100 outputs(100*500). Kriging is suitable for this situation? Or reduce the output dimension by some methods.
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Dear all. The Normal distribution (or Gaussian) is mostly used in statistics, natural science and engineering. Their importance is linked with the Central Limit Theorem. Is there any ideas how to predict the numbers and parameters of thos Gaussians ? Or any efficient deterministic tool to decompose Gaussian to a finite sum of Gaussian basic functions with parameter estimations ? Thank you in advance.
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For Central Limit Theorem, the random variables are not necessarily gaussian but they have to be independent and identically distributed (in classical CLT). They can come from any distribution. Moreover, CLT is an approximation. Do you have a prior knowledge that the resultant gaussian variable is composed using gaussian variables? In that case, using the convolutional properties of normal random variables can give you an idea.
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Dear all. The Gaussian function is mostly used in statistics, physics and engineering. Some examples include:
1. Gaussian functions are the Green's function for the homogeneous and isotropic
2. The convolution of a function with a Gaussian is also known as a Weierstrass transform
3. A Gaussian function is the wave function of the ground state of the quantum harmonic oscillator
3. The atomic and molecular orbitals used in computational chemistry can be linear combinations of Gaussian functions called Gaussian orbitals
4. Gaussian functions are also associated with the vacuum state in quantum field theory
5. Gaussian beams are used in optical systems, microwave systems and lasers
6. Gaussian functions are used to define some types activation function of artificial neural networks
7. Simple cell response in primary visual cortex has a Gaussian function modeled by a sine wave
8. Fourier transforms of Gaussian is a Gaussian
10. Easy and efficient approximation for signals analysis and fitting (Gaussian process, gaussian mixture model, kalman estimator , ...)
11. Discribe the Shape of the UV−Visible Absorption
12. Used in Time-frequency analysis (Gabor Transform)
13. Central Limit Theorem (CLT) : Sum of independent random variables tends toward a normal distribution
14. The Gaussian function serves well in molecular physics, where the number of particles is closed to the Avogadro number NA = 6.02214076×1023 mol−1 ( NA is defined as the number of particles that are contained in one mole)
15. ...
Why Gaussian is everywhere ?
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The Gaussian function serves well in molecular physics, where the number of particles is closed to the Avogadro number NA = 6.02214076×1023 mol−1 ( NA is defined as the number of particles that are contained in one mole)
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I would like to use CLT (Central limit theory) to substitute the linear combination of sincs with random coefficients C_k drawn according to chosen constellation with a complex Gaussian process with the same mean and covariance.
What is the way to do it?
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Hi,
It deals with Gaussianity of OFDM signal, but it is quite similar to your problem: just replace cosinus by sinc and it should work.
Best regards,
Vincent
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What's the difference between a multivariant Gaussian and a Gaussian mixture model? Do they refer to the same thing?
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the height, weight and age of a kid in school are random variables, loosely related together. they, together, form a multivariate distribution
on the other hand,
if you measure the size of apples from a certain farm, and you notice that this random variable does not have the usual "bell curve" distribution, but rather 2 humps side by side, that's a gaussian mixture.
what could be the cause of this two-bell curves? that there are two species or breeds of apple trees, and the farmer collects them all together and sells them without discriminating the two species.
or for example, you buy milk from a farmer and decide to measure the level of a certain protein in the milk, and notice that the data doesn't follow the normal bell-curve, but has 2, 3 or even 4 humps. you later discover that this farmer has goats, sheeps, camels and cows, he fills the milk of each animal in separate bottles, but sells the bottles all together without discrimination in one shipment.
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I'm dealing with a supervised problem which includes three features. My main purpose is to find the relationship among these features which is complicated. I'm looking for a straight relationship, not a multistage one. Support Vector Regression and Gaussian Process Regression include multiple stages but they are not proper for me. Which algorithm do you recommend to me?
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following
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I have read multiple articles that have used machine learning algorithms (convolutional neural network, random forest, support vector regression, and gaussian process regression) on cross-sectional MRI data. I am wondering whether it is possible to apply these same methods to longitudinal or clustered data with repeated measures? If so, is there an algorithm that might be better to use?
I would be interested in seeing how adding longitudinal data could improve the performance of these types of machine learning models. So far, I am only aware of using mixed effect-models or generalized estimating equation on longitudinal data, but I am reading books and papers to learn more. Any advice or resources would be greatly appreciated.
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Hello Robert, there are extensions of recursive partitioning and trees for longitudinal and clustered data. They essentially include a mixed model element into the algorithm. I have used the RE-EM algorithm in the past (see DOI: 10.1007/s10994-011-5258-3 and DOI: 10.1016/j.csda.2015.02.004). There are also binary partitioning for continuous longitudinal data (DOI: 10.1002/sim.1266) and mixed-effect random forest (DOI: 10.1080/00949655.2012.741599). Implementations can be found in R packages: REEMtree, longRPart2, MixRF.
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Additionally, can someone comment on the following:
I am generating a 1D data using a squared exponential kernel. If I use the data to learn the hyperparameters using maximum likelihood approach, then what are the conditions under which I will get the same hyperparameters as I have used for generating the data.
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Hey everyone,
currently, I am working with Gaussian process latent variable based models. In literature, the model likelihood is discussed for model selection.
Unfortunately, this does not work for my application. Currently I am using the log likelihood and the reconstruction error. The model likelihood increases and the reconstruction error decreases with increasing dimension/inducing points. BIC doesn't make sense in this context (and behave similar...).
Are there better parameters for model selection?
All the best,
Will
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Thank you Karthika .P ,
I know these publications - I already implemented an ARD based model selection approach. But I have following problems:
- I can choose the dimension of a given model using the ARD values
- The number of inducing points is still unsolved
- An analysis of reconstruction error and model likelihood shows, that more dimensions and inducing points will leads to better results (this is a good thing)
- For my application, I want to find the information content in the latent space. I could do this using supervised learning afterwards (e.g.: Boruta [1]), but I do not want to do that because I am interested in the information content of the latent space itself without prior knowledge (such as labels).
- I do not want to use approaches based on the fitted GPLVM model.
So ARD, log. likelihood and reconstruction error are not appropriate in my context.
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Hello everyone
I have successfully drawn CuO structure in Gauss view through PBC, I need to know what are the appropriate parameters in functional and basis set in order to successfully optimize the crystalline structure. Please refer to some literature, websites and forums regarding this
thank you
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People uses different basis sets bu the most common is B3LYP /6-311G**dp. Try using this, it takes less time .
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what are the new upgrades in Kriging methods ? I am thinking about variable distributions for the Kriging predictor? and I want to know that is it rational and could it be a proper upgrade to the method for learning/predicting applications?
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Hossein
Your claims are all wrong. The only way you could determine "accuracy" is if you can compare "true values" with "interpolated values". At the locations where you know the true values there is no need to interpolate. The usual forms of the kriging estimator and the kriging equation do not take elevation into account so any claim that it is best for mountainous areas has no theoretical justification.
You need to consult a good book on geostatistics, whatever you are using as a reference is wrong.
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I'm using fitrgp toolbox for Gaussian process Machine learning on MATLAB. But till now all my work has been in real numbers. Now I need to include complex numbers in my project. But fitrgp does not accept complex training data. Is there any way to get around this situation, like a substitute toolbox or some way to include complex numbers in the same toolbox?
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Can you elaborate in what context you are trying to use complex values? If you are working with spatial domain, for example, you can perform a coordinate transformation and obtain equivalent real values. So, it really depends on what data you are working with.
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I am trying to simulate the molten metal flow of TIG welding in ANSYS Fluent by giving 30 iterations per time step. I observed that initially at each time step, convergence occurred at around 16th or 17th iteration. But when the simulation progresses, the convergence shifted towards larger iteration (like 20th, 25th, 30th..) and finally started diverging after reaching half of the total time steps.
What are the possible reasons of this and how can I keep the simulation running with convergence at around same iteration?
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Dear Balasaravanan Karthikeyan Thank you so much. Could you please clarify below.
1. How do we do averaging of flowfield? Does this relate to the input Boundary conditions? Presently, I am using a UDF to define heat flux input along the weld line at the top by defining it as a "wall". And, the time step size I used is 10-5. If I decrease the time step size any further, it will really take a very long time for the simulation to complete.
2. Also, I observed one thing while running this simulation. Initially, I gave 30 iterations per time step. Note that total no. of time steps is 50000. When I noticed that convergence is not occuring by 30 iterations (after 30,000 timesteps), I paused the simulation and increased no.of iterations to 50 , corrected the no. of time steps to 20,000 and resumed the simulation again. Then I noticed that it started converging before 20 iterations at each time step. But, this was also not consistent, the convergence slowly shifted towards higher iteration again i.e, beyond 30 iterations. Now, I have again paused the simulation (after 37000 time steps), updated no. of time steps to 13000 and increased no. of iterations to 60 per time step. Now, its converging at 31st iteration.
Could you please help me interpreting this kind of convergence behaviour as to why the convergence is occuring at an earlier iteration if I am increasing its value?
Are these kind of modifications which I am doing valid? Do they effect the solution in any way?
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Specifically, TA spectra in solution.
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If lots of bands in the visible are asymmetric, why not using the classical damped harmonic oscillator model (CDHO) instead of the Lorentz-profile? The latter has been derived by Lorentz in 1906 (hence the name... ;-), but the derivation includes 3 approximations and the first forces band shape to be symmetric, in contrast to the CDHO, where for higher oscillator strength the bands become highly asymmetric... see, e.g.:
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Consider a single mode Gaussian beam entering a 0.75 NA objective. I made measurements of beam's FWHM around the focus. It looked like before the focus, the beam converges according to NA=0.75. But after the focus, NA is somewhat larger - I saw this in 3 attempts. Is this normal? NA=0.75 is not associated with a single mode beam usually.
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Could you try with a collimated flat-field beam ? Maybe it's just the gaussian divergence of the laser showing up but it's strange it only appears after focus.. What is quantitatively the NA variation after focus ?
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I am doing DFT calculation on metal complex. I got this error: "Bad data into FinFrg.
Error termination via Lnk1e in /usr/local/g09l/g09/l122.exe at Wed Nov 20 00:00:58 2013.
Job cpu time: 0 days 0 hours 1 minutes 0.9 seconds."
Please suggest some solutions.
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I fought with the same error before finding the solution.
In my case, the problem was that the two fragments in my molecule were by default choosing their unpaired orbitals to be alpha spin orbitals, which can't be the case for a singlet PES. The solution was to put a negative sign in front of the spin multiplicity for one of the two fragments.
More details on the usage of the negative sign for the spin multiplicities of fragments can be found here: http://gaussian.com/molspec/
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I have recently been working on applying ML algorithms for time series prediction (forecasting demand of item). I am a bit confused somehow. So, my questions is as follows
1.Does the performance of these algorithms usually depends of the nature of the dataset i.e descriptive characteristics like mean, max, min etc. The machine learning algorithms i applied includes, Gaussian processes, backpropagation neural network and support vector machine.
2.I found Gaussian processes performs better than the rest but i am not too convinced with my results since the RMSE is still high for all algorithms i tried. Below is a summary for data i have.
item_1
Min = 100
Max = 40200
Mean = 11849
RMSE = 11756.5
I used WEKA forecasting package i have attached a time series plot
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The quality of prediction depends on the relationship between the attributes and your label. You may want to check R^2 statistic. This will tell you how much of the variation is explained by the attributes. Usually, some sort of feature engineering is required along with the use of some kernel, when there isn't a linear relationship.
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Dear Altruistic
I am new with Gaussian, I have optimized a Graphene structure by using Gaussian with DFT method and 6-31G basis set. But after optimization the bond length between carbons have changed from original  one and in the optimize structure different carbon carbon bond length also different.
could any one help me to resolve this ? 
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I have read about What Bhat have done about this MDCEV model but I am eager to know more about this.
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Hi there, I could not find a transition state for some reason. I have provided my input and output file. For some reason the output did not have an imaginary frequency but seemed to progress like a reaction.
Please not that the OH radical is the reason why I have an 0 2 charge and multiplicity.
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Mr. Uddin,
There are test files, here:
Files 302 and 303 deal with QST2.
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Can someone explain why using Gaussian function for fitting the photoluminescence spectrum, we must change the unit of wavelength (nm) to unit of energy (eV)? I see someone doesn't change unit of wavelength (nm) in to unit of energy (eV). I wonder about their method?
Thank you so much for your answer.
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Dear all!
Almost all of you are wrong. You are giving wrong answer to the question. I just repeat my answer from here:
"
First I would say that fitting Gaussian to absorption spectra where independent parameter is the wavelength is a mistake (actually not just Gaussian, but also Lorentian). If you want to make a Gaussian fitting you should do it on frequency (energy) scale. (Same is true for making derivatives.) Consequently a Gaussian peak on the wavelength scale is not symmetric, it is very much asymmetric, having longer tail in the longer wavelegth side. That is why UV peaks have a long tail to the visible region. So ALWAYS fit functions on a frequency scale!
Second, as a first try I would fit Lorentzian function. A single transition always has a Lorentzian shape. Gaussian arises if many single transitions are convoluted. It happens very often but single transitions are not so rare. Even if you have a complex spectrum it is worth first to fit with the sum of several Lorentzians.
Using derivative does not mean that you have eliminated the baseline problem. Baseline is eliminated by deriving the function ONLY if it is a linear baseline (in this case it will add a constant baseline only to the derivative spectrum). If the baseline comes from the tail of other peaks, making derivative spectrum would not solve your problem.
If all these problems are solved then I agree with all answers above. You should fit a polynomial baseline together with the Gaussian. However you should be very careful. If the baseline fitting result in a polynomial where maxima and minima exist, you can easily add false peaks to your evaluation (with both positive and negative amplitude) As a rule baseline should always be a MONOTONIC function, therefore polynomial fitting is acceptable if it results a monotonic fit. It is very useful if the fitting program lets you investigate the individual functions fit."
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I have one drug candidate in diastereomeric mixture. Is it possible to identify the number of isomers in diastereomeric mixture by using the second derivative calculations and Gaussian curve fitting analysis of DTG (Differential Thermogravimetric analysis) curve by using OriginPro 8 software?
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Dear Sameer....Unfortunately, the TG is not the choice for such identification of isomers. We have studied a large number of organic compounds (preferably solid) by TG and all isomers show the same behavior. Isomers are almost identical in the thermal decomposition profiles. However, if the isomers differ with their melting or even boiling points, there may be some degree of identification and discrimination between them by the DSC technique following their melting or boiling peaks.
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What are some advantages of using Gaussian Process Models vs Neural Networks?
An example explain that's advantages.
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Two main advantages come to my mind:
1. Gaussian Process (GP) directly captures the model uncertainty. As an example, in regression, GP directly gives you a distribution for the prediction values, rather than just one value as the prediction. This uncertainty is not directly captured in Neural Networks (see for example https://arxiv.org/abs/1506.02142)
2. When using GP, you are able to add prior knowledge and specifications about the shape of the model by selecting different kernel functions. For example, based on the answers to the following questions you may choose different priors. Is the model smooth? Is it sparse? Should it be able to change drastically? Should it be differentiable?
If you want to learn the basics of GP, I recommend this lecture by Nando de Freitas: https://www.youtube.com/watch?v=4vGiHC35j9s
A collection of Gaussian process models is available in GPstuff toolbox : http://research.cs.aalto.fi/pml/software/gpstuff/
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what are the advantage of Gaussian process regression in hydrology compare to other data driven techniques,
  
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thanks Mr Sihag
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Hi,
I have a big dataset with mat format (used for Matlab). It is a giant matrix. Its size is about 280 MB. I am trying to input it into R using the function 'readMat' in package 'R.matlab'. However, it took soooo long time (about 20 minutes) and then it threw out an error 'cannot allocate vector of size 10.7Gb'. Though it can be easily inputed in Matlab (about 1 minute).
Does anyone know how to input a large mat dataset into R quickly? And why the memory stuff is OK in Matlab but not in R?
Thanks,
Lei
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Thanks, Saul! That package 'data.table' works very well. It cannot read mat directly and I have to convert mat into csv firstly, but it reads csv very quickly. It did solve my problem!
Thanks again,
Lei
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I am trying to use "volutil" to combine ils outputs (.dx occupancy maps). The error I got is "No weight detected in DX file."
Any ideas?  
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Well, i did solve this question. Just needed to sit down and write a code in R that actually calculates the average over separate .dx files. 
Somehow I could not manage to make volutil code run.
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For a relative large event, it usually has several sub-events and we get a large set of data. In order to do stacking or for visualization purpose, it's better to flip the traces with opposite polarity. Could you tell me some simple and effective method to detect it. Some crude method like finding the maximum on displacement record usually failed if the waveform is complex. Thanks!
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Since you say its a big event and big events have finite source area which then radiates energy in all azimuths which is not same because of the Doppler effect.  As Weijia mentioned cross-correlation would be best to detect it, as for as stacking is concerned it would not work from all azimuths. But if the event is deep enough then STF is more simple than the one which shallow (like recent Nepal Eq). You might wanna have a look into these: 
For the cross-correlation
For big shallow event with multiple sub-events
I hope it helps in some way
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Hello, I am very new user of Gaussian. I started the optimization of the connected two amino acids. Calculation was finished, and I would like to get the optimized structure. How can I know success of optimization? and get the optimized structure?
Please, advice me.
Thank you.
B.M.
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Gaussian and any other QM software finishes optimization after it reaches a certain convergnce threshold in the self-consistent scheme. If using stadard g09 values, they are maximum and rms foce with respect to the previous step and maximum and rms displacement with respect to the previous step. As soon as they are lower then defined values gaussian claims to find the optimized structure by outputing: "Optimization completed. -- Stationary point found."
The geometry of the optimized system is printed next after this message. You can also easily visualize it (as well as all the steps of the optimizaion) in any QM visualization software, like molden avogadro and so on.
Mind, however, that this geometry is not necessarily a potential energy surface minimum - in order to find if it is, you should do frequency calculations on the optmized geometry (keyword "freq" in gaussian input).
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I would like to simulate ambient vibration in a numerical model such as a MDOF shear building. In some cases, the use of random Gaussian white noise can be a solution. Is it a plausible approach?
Thank you
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Moreover, you can simulate the ambient vibration caused by wind in your numerical models. For this goal, you need to introduce with aerodynamic forces such as self-excited forces and buffeting forces in wind-induced ambient vibration simulation. Although these forces are usually dominated in bridges. The following reference may be useful:
He, X., Moaveni, B., Conte, J.P., Elgamal, A., Masri, S.F., (2008). "Modal Identification Study of Vincent Thomas Bridge Using Simulated Wind‐Induced Ambient Vibration Data." Computer‐Aided Civil and Infrastructure Engineering 23(5): 373-388.
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Hi,
I am trying to fit Gaussian process to learn a distribution from input sequence to output sequence. I am relatively new and have several questions:
1) For time series prediction problems, if you have a sequential input you can feed them without stacking inputs into a vector while using RNNs or LSTMs. Do Gaussian processes have such a structure? If no, is it still make sense to use GPs to learn output sequence from input sequence?
2) When I try to fit GP to training data with 400 samples and 18 features it has really difficult time. Is there a way to batch the data and use the learned parameters from one batch to another as in neural networks.
Thanks in advance.
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Hi,
Part 1:
It does make sense to use GPs to model time series data.
In the simplest setting, we can consider having a set of (x,y) pairs, where x is the time and y is an observation/output at that time. To train a GP model, we just need to pick a mean and a covariance function for the x's. It is common to use 0 for the mean (and subtract off the empirical mean before training). There are many valid choices for the covariance function (see, e.g., Rasmussen and Williams, 2006), but a common one is the squared exponential function (commonly called the radial basis function in the context of NNs). Intuitively, this function implies that we expect observations close together in time (i.e., close x values) to have similar observed values (y's). If you expect strong periodic behavior of the inputs, covariance functions based on trigonometric functions are a reasonable choice.
While quite a bit of theory has been developed to explain what is really happening in training/inference, I recommend the GP chapter (17 for version 2.15.0) in the Stan user manual: http://mc-stan.org/documentation/ for a thoroughly explained implementation, supplemented with the Rasumussen and Williams book mentioned above for more detailed theoretical explanations.
Generalizing the model to multivariate inputs (such as the 18-dimensional space you mention in part 2 of your question) is straightforward (at least with the squared exponential covariance function). The Stan manual covers this (pp. 245-246 in version 2.15.0 of the manual).
---
Part 2: Unfortunately, I have only GPs for time series in low-dimensional settings, so I have not really experienced this problem. You may try searching for "online" or "sequential" training of GPs. For example, [Csató, L. & Opper, M. Sparse On-Line Gaussian Processes. Neural Computations, 2002, 14, 641-668] is highly cited and seems like it could be relevant.
---
I hope this helps at least get you pointed in the right direction.
Have a good day,
Brandon
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If the amplitude distribution is given how can we calculate the total energy? 
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If the field amplitude is known, then get the intensityfrom  |E(x,y)^2|. Now, you need to integrate this over x and y, times dx dy, to have the power transferred. Energy is this power integrated over time (if stable then simply maultiplied by time). If you relate to pulses then their energy content is the integration over time. Can also be obtai ned from dividing average power by the pulse frequency rate...
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I am using mixed z-matrix and Cartesian coordinates in ONIOM with Gaussian 16 (z-matrix for high layer and Cartesian for low), and the freeze code for the Cartesian atoms is not working. Do I need to specify something in the route card to direct the program to adhere to this coordinate specification? I have no constants in my internal coordinates, but I need to hold one atom fixed in Cartesian coordinates.
Thanks in advance.
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You can enter internal coordinates in Cartesian coordinates.
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I have a little problem with small frequencies (<50-100 cm-1) in optimization jobs when using Gaussian. Obviously the problem is when comparing free energies. In a recent paper I found this line: "Truhlar’s quasiharmonic correction was applied
in order to reduce error in estimation of entropies arising from the
treatment of low frequency vibrational modes as harmonic oscillations
by setting all frequencies less than 100 cm-1 to 100 cm-1".
Does anyone know how to do this and which commands are required in Gaussian. Otherwise if anyone as an other option to remove small frequencies it would be very welcome.
Thanks!
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Dear Ivan,
It's true that you cannot avoid this frequencies in the optimization. There are two approximations to correct this little frequencies (one done by Truhlar, and other by Grimme). The Truhlar approximation is based on setting all the frequencies lower than a cut-off value to this cut-off. The Grimme approximation is based on using the rigid rotor approximation for the lower frequencies and the armonic one to the rest (using a dumping function to avoid technical problems).
I developed a free code to do these corrections automatically (with Prof. Robert Paton in University of Oxford). In addition you can change the temperature, concentration and other features in the thermochemistry calculation. Here is the website:
You can cite it using the associated DOI in the webpage.
Best,
Ignacio
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Hi,
I need to calculate gradient of energy at a given geometry without doing the full optimization. In GAMESS-US, one can set a "gradient" type of calculation for that. In G09, I usually do Opt (MaxCycles =1) and. The G09 does the gradient calculation but naturally produces .chk and .rwf files complaining about non optimized structure.
Is there is a way to do it more conveniently? Sure, I could just delete all unnecessary files after the calculation is finished but may be you have better ideas...
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Well, in that case discarding the chk files might be ok, if your calculations aren't too large. Disk space is so cheap that this shouldn't happen, anyway. But I've just seen it so many times, especially with gradients or second derivatives, that people simply discard days of computational effort.
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I want to perform calculation in solvent 2,2,2-Trifluoroethanol in gaussian but its not defined in gaussian. Please help me out how should I proceed for the same.
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Hi Pansy
Thanks for update that Gaussian16 has this solvent.
I have been applying the same approach as suggested by you but I am using Gaussian 09 for the calculations.
Thanks for your help.
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Hello, I am trying to running a frequency calculation with gaussian for a dimer that is made by benzene and bromine fluoride at T-shape. After finding a stationary point in the optimization, the software starts the frequency calculation, but then the latter one aborts without any error message... The last line in the output file is:
Using OV2 memory method for fx*t*t/D, MaxI= 43 DoOO2=F NP= 8.
Attached there are the input and the output files.
Anyone can help me, please?
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First, rerun it from checkpoint with removing counterpoise and opt (leave just freq) and see if it works.
The likely problem is however the lack of memory - freqs for MP2 require prohibitive amounts of memory, particularly in large basis sets.
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I want to calculate with different temperature on gaussian 09 and I do not know how to do it
Help me please
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Dear Noureddine,
In Gaussian 09, such an expectation can very simply be achieved via definition  temperature and pressure within frequency calculation over the optimized geometry. For instance, assume you are going to include 300K and 2atm in your calculation. You can use the following command line:
"functional/basis set  freq temperature=300.0 pressure=2.0"
I hope you find it helpful.
Regards,
Saeed   
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I have passed the white Gaussian noise from a low pass filter in labview and resulting it should be colored noise. I get the signal and I saved random number in Excel file. Could someone suggest that how can I make sure that the random number saved in Excel file is actual colored noise.
Any help/suggestion would be welcome.
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Thank you very much all of you for your useful suggestion. 
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Consider the following expression xHAx, where x is a known vector, i.e. a determinisitc parameter, and xH its hermitian, and A is a hermitian, positive semi-definite matrix constructed as the summation of D rank-one matrices of the form didifor i=1,...,D. In this case, the vectors di are distributed as a standard complex Gaussian (zero mean and unit variance).
The question is which is the statistical model of xHAx?
Thanks in advance.
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Data presented in abstract well is not good for statistical modelling, because the phenomena itself must be related with the explanation and the model. Probably a Bootsrap approach could be a better option for your model, but is necessary an approximation of the size of the matrices and an empirical explanation about what the data is related on. Good luck. 
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I am looking for a derivation of conditional simulation for Kriging also known as Gaussian Process Regression. Conditional simulation allows to simulation realization based on the modelled Gaussian process conditioned to the given data.
Can someone help?
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Please note that there are no distributional assumptions used in deriving the equations for Simple kriging or Ordinary kriging or Universal kriging so it is very mis-leading to refer to kriging as "Gaussian process regression". It is true that under the under the assumption of a multivariate Gaussian distribution that the Simple kriging estimator is in fact the conditional expectation.
As to simulation there are several different algorithms for conditional simulation and each has its own advantages and dis-advantages. Your choice should be at least partially  based on which properties you want to preserve, e.g. the variogram model (spatial correlation structure),  expected value of the random function, probability distribution of the random function. The underlying assumptions are different for each of the algorithms.
Goovaert's book is certainly one good resource, the book by Chiles and Delfiner (Wiley publication) is a good choice
What is the phenomenon you want to simulate and do you want to simulate point values or averages over "blocks" or images. What kind of conditioning data do you have. What do you want to use the simulated data for?
Note that it is likely you will want to generate multiple realizations and there is no real way to know how many is enough. Most often data is simulated on a grid so you have to decide the mesh for the grid. All of this has an impact on the computational demands although with present computing power that is not usually a big factor.
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I have read many of papers in which they have carried out calculation of potential energy scan for molecule in singlet and triplet states and have investigated the crossing point of singlet and triplet potential energy diagrams. Are these rigid or relaxed scans?
I want to investigated the potential energy diagram for HXeXeF molecule in singlet state and triplet state (at the singlet state geometry) along the H-Xe coordinate to obtain crossing point of them. I fixed distances of Xe-Xe and Xe-F and used scan keyword in rout section.Is it right?
I attached gaussian output files.
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When you use the Scan keyword directly, the scan is always rigid – in your case, the angles, dihedral, and HXe distance will be fixed to whatever your initial input file specifies.  If you want a relaxed scan, you have to select Opt=ModRedundant, then in the additional input section this method requires, you specify the geometric parameters you want to step, followed by an "S", then a step size, then a number of steps; ideally, you will want to review that section in the Gaussian manual under keyword "Opt".
Because the scan you conducted is rigid, there should be no difference between the geometries generated and calculated in each run (since the parameters, step sizes, and step counts are the same), and the multiplicity you used should give you the lowest singlet and triplet states; if anything looks peculiar when you plot the energy, however, you might need to add keyword "Stable" to ensure that you haven't accidentally converged to a higher singlet or triplet (in my experience, this is exceedingly rare; what is more common for DFT is spin state contamination, which you can check by looking at S-squared before and after annihilation of the spin contaminants – but your singlet run may not give you an accurate representation of this electronic feature due to the nature of the RHF method).
If, however, you want a relaxed scan, you will have to do something completely different to get the triplet energies at the singlet geometries – simply switching to a relaxed scan with your current input files will give you the singlet and triplet stepping at each of their particular optimized geometries.  There may be a better shortcut, but the simplest thing I can think of is to run the singlet relaxed scan first, extract all the optimized geometries, then construct a multistep energy-only job with these geometries but specifying a triplet electronic state.
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The Fourier transform of the Guassian signal is again a Guassian signal. Is it from the duality property of the Fourier transform?
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Linear transformation does not change the distribution. But what do you mean? Fourier transformation is the amplitude or squares? The amplitudes of a Gaussian distribution. Squares is a different division. This chi-squared distribution.
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I want to compare between blending data using Regression Kriging and Bayesia Kriging. What is the advantage of Bayesian Kriging compare to Regression Kriging? Anyone has a recommended link/journal for learning Bayesian Kriging? Many thanks in advance
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You should also consider cokriging. Exactly what do you mean by "more powerful"? I.e., how would you quantify "power"?
Regression kriging usually means combining in some way regression and kriging. In particular where the expected value of the random function is nonconstant, e.g. it is a polynomial function of the position coordinates or is function (usually a low degree polynomical) of another spatially distributed variable, e.g. elevation in the case of precipitation.
Precipitation data is nearly always "point" data whereas satellite data is non point data  (there is a pixel size) so you must compensate for the difference in data support. Regression doesn't do that and in general Bayesian modeling doesn't either. I suggest that you need to look more at the literature on combining rain gage data with Doppler rain data, this is more analogous to your problem. You will see that cokriging has most often been used
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Gaussian09D: After an excited state computation has finished, the requested excited states are listed along with the atomic orbital transitions that are supposedly taking place during the excitation. How does one determine what type of transition is taking place?...in other words, is/are the transition/s pi-pi*, sigma-sigma*? How do you determine which one it is? I am using the following scheme: td=(50-50,nstates=20) rb3lyp/6-311g(d,p). Thank you for your time! :)
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Mr. Stoicu,
In addition to the discussed by other particupants, you can use the irreducible representations and character tables according point groups within the framework of groups' theory. Character tables are well known (Ref. 1, for example).
The excitation energies, oscillatory strengths to corresponding transition state from the character tables (attachment) can be directly obtained by Gaussian, using the symmetry adapted cluster method. Details are shown in: http://www.gaussian.com/g_tech/g_ur/k_sac_ci.htm
An example of H2O (C2v, character table: ref. 1, page 72, attachment) is given here. The output yields the corresponding symmetry states, excitation energies, intensities, oscillatory and rotatory strengths. There are shown data about singlets and triplets. The comparative analysis with the character table as shown (attachment) enables to assign a transition type in notation s-s*, n-s* and more, on the base on corresponding data about the transitions given in the symmetry state notation. As it is shown in the attachment "s" and "pz" serve as basis for the symmetry state A1.
Data about H2O (C2v):
SAC-CI/6-31G*
*******************************************************************************
Singlet A1 *********************************************************
### 1-st ### --- 2nd state in this spin multiplicity ---
Total energy in au = -75.725640
Correlation energy in au = 0.259552
Excitation energy in au = 0.393502 in eV = 10.707733
*SINGLE EXCITATION
4 6 0.96852 3 7 -0.07035
4 9 -0.04774 5 10 -0.03798
2 6 0.03419 4 13 -0.03223
*DOUBLE EXCITATION
4 6 3 7 -0.13086 4 11 4 6 -0.10256
4 6 4 6 -0.08815 5 10 4 6 -0.07591
4 7 3 6 -0.07029 4 6 3 12 -0.06819
............................................................
-------------------------------------------------------------------------------
Transition dipole moment of singlet state from SAC ground state
-------------------------------------------------------------------------------
Symmetry Solution Excitation Transition dipole moment (au) Osc.
energy (eV) X Y Z strength
-------------------------------------------------------------------------------
A1 0 0.0 Excitations are from this state.
A1 1 10.7077 0.0000 0.0000 0.6311 0.1045
A1 2 19.3404 0.0000 0.0000 0.6813 0.2199
A2 1 10.7127 0.0000 0.0000 0.0000 0.0000
A2 2 29.9828 0.0000 0.0000 0.0000 0.0000
A2 3 32.0696 0.0000 0.0000 0.0000 0.0000
B1 1 8.4130 0.2524 0.0000 0.0000 0.0131
B1 2 31.8784 -0.0203 0.0000 0.0000 0.0003
B1 3 32.7984 0.0653 0.0000 0.0000 0.0034
B2 1 13.1660 0.0000 0.5983 0.0000 0.1155
-------------------------------------------------------------------------------
-------------------------------------------------------------------------------
Rotatory Strengths
Symmetry Solution Excitation Elec. Mom. * Magn. Mom. (au) Rotatory
energy (eV) X Y Z strength
-------------------------------------------------------------------------------
A1 1 10.7077 0.0000 0.0000 0.0000 0.0000
A1 2 19.3404 0.0000 0.0000 0.0000 0.0000
A2 1 10.7127 0.0000 0.0000 0.0000 0.0000
A2 2 29.9828 0.0000 0.0000 0.0000 0.0000
A2 3 32.0696 0.0000 0.0000 0.0000 0.0000
B1 1 8.4130 0.0000 0.0000 0.0000 0.0000
B1 2 31.8784 0.0000 0.0000 0.0000 0.0000
B1 3 32.7984 0.0000 0.0000 0.0000 0.0000
B2 1 13.1660 0.0000 0.0000 0.0000 0.0000
-------------------------------------------------------------------------------
Rotatory Strengths are given in 10**(-40) cgs (esu * cm * erg / Gauss) units.
STEP #SATEI# Monopole Intensity Calculation
Symmetry State I.P. Intensity
------------------------------------------
A1 1 13.386 0.94526
2 35.161 0.00622
------------------------------------------
B2 1 18.911 0.96269
------------------------------------------
.......................
Ref. 1. D. Barcelo (Ed.) Comprehensive Analytical Chemistry (Wilson and Wilson's), Vol. XXXV,(A. Christy et al. Modern Fourier transform infrared spectroscopy), Elsevier Science B.V., 2001, Amsterdam, pp.1 - 355.
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The space grid dimension in FDTD depends on the frequency we choose to operate on. When considering sine wave excitation, we can find space grid value from the frequency chosen. But, how to find the space grid value when the excitation is taken as guassian pulse. the excitation is given for a microstrip line with width(along x axis)=2mm, length of the line(along y axis)=20mm and height of the substrate(along z axis)=0.8mm. with these specifications, i had found dx, dy and dz as one tenth of the values and the time step as (least dimension)/(2*speed of light). but the field values extend upto infinity after a few time steps. can anybody tell were have i gone wrong.
thanks.
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The spectrum of a Gaussian is another Gaussian, so it is not band-limited and cannot be sampled on a grid (in theory).  In practice, you can truncate the Gaussian when it reaches a small enough amplitude.. e.g., -60dB or machine epsilon.  You can work out the exact values of the corresponding frequencies (from analytic expressions), and then you can figure out your grid spacing.  Hope that helps.
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I have some multivariate Gaussian random variables which I want to whiten them. During decorrelation procedure the means of variables change. Is there any way for whitening the correlated variable that does not change the mean?
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Thanks for your answer. If I understand your sentences well, it is required that I know the mean of each variable and then subtract the means from each variable to center all of them about a specific value. However, in my problem the mean of variables are different and are unknown for me.
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Hello everyone,
I am doing my research on optical comb generation. During my research i am facing some problem. I got some results but i could not remove the ripples of the spectrum with the Gaussian filter. How can i flat the the spectral lines by using any components in optisystem?
- Thank in advance
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As Mr. Muhammad Nasir Commented, you are better off filtering the original signals first hand. Consider this, 
 Once you have a frequency pattern (it is a combination of lows, mids and high frequencies) scattered across the time-domain. Now, when we talk about such a composite structure, we also look at harmonics and resonance that tend to appear at the respective time frames (obviously I am talking about spectrum sensing and analysis for which we have to look at the signal both in frequency and time domain). 
So, when we say we need to remove some noise or distortion, we are looking at the ripples or some may refer to them as harmonics that appears in those quad cycles.  They can be removed or suppressed (more precisely) by using filters/windows. 
But in your scenario, you have a composite spectrum and it appears to me that you want a flat spectrum which is roughly referred to as chopping off. 
When you try to chop off the signal using any filters (let it be Guassian), it also chops off the actual spectrum and the added noise spectrum on top of that. So, there is no viable solution to remove the noise from such signal. 
There are many complex ways in spectrum analysis and some include:
  1. Signal regeneration (receiving or processing end)
  2. Median Filtering
  3. Reverse transforms
  4. Dynamic Filter window selection
I would be more than happy to discuss it greater length, if you could picture the whole scenario. 
Please find attached, an article, that I believe could be applied to your work
cheers
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I'm reading the paper attached and there is something I don't understand. The paper says that the Gaussian pulse which has the following parameters was used in the simulation.
Order : 10
Peak power : 10
FWHM : 1 ns
Chirp rate : 5.4π THz/ns
What is the chirp rate? And what is the relationship between the chirp rate and the chirp parameter in the formula of the super-Gaussian pulse?
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@Vincent,
As you say, chirp rate is rate of change of optical frequency with time.
However, a super-Gaussian pulse is not necessarily chirped.  With super-gaussian constant C equal to zero, the optical spectrum is still Fourier-broadened, but the pulse is not chirped.
Optical field U = A exp( -(1+i C) (t / t0)2m/ 2 ) exp( i omega_c t )
instantaneous radian optical frequency = d(phase) / dt
 = omega_c - m (C / t) (t / t0)2m 
When the super-Gaussian chirp constant C is zero, the instantaneous optical frequency is constant and equal to the unmodulated carrier frequency omega_c.
@Harutaka:
Note also that when C is non-zero and the super-gaussian order is greater than 1, the chirp rate varies with time through the pulse.
radian chirp rate = -m(2m-1) C t(2m-2)  / t0m
This is not what Vanvincq et. al show in figure 3 of their paper, where they specify a linear increase of optical frequency with time, so that the chirp rate is constant.
Are you working with a mathematical model, a simulation package or real world?
Mathematically, you can add a linear chirp by multiplying the time-domain pulse by a phase shift which varies quadratically with time: 
linearly chirped pulse = pulse( t ) x exp(i alpha t2/ 2).
In the lab (or simulation), an unchirped Gaussian (not super-gaussian) pulse is transformed into a broader, linearly chirped pulse by chromatic dispersion.  You would then need to re-shape into an order 10 super-gaussian, for example using an appropriate intensity modulation scheme. 
Using real-world optical fibre, there are complications associated with non-linear chirp due to Kerr effect Self Phase Modulation.  With sufficiently narrow pulses, diffraction gratings can be used to produce the required temporal broadening.
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I am running a DFT calculation using Gaussian 05,,, but the output / log file shows the above mentioned statement. I tried with all possible changes which can be made in input file and checked the space b/w the lines and keywords, but unable to get the converged structure. Can any one help me to solve this convergence problem?
My Input file is like this..
%mem=2GB
# opt freq b3lyp/6-31g geom=connectivity
Title card
0 1
C -6.02619527 9.44527291 -0.71253003
C -4.97668356 9.89555985 -1.74430456
C -5.41433211 9.54127357 -3.18798470
C -7.65683239 10.03305367 -2.44048523
C -7.30718981 10.22873199 -0.96683834
H -5.27098963 9.94279746 -4.16774469
H -4.82659707 10.95398877 -1.66069636
H -6.20196164 8.40208993 -0.83104254
H -7.85894719 9.00324965 -2.64166873
H -7.13425811 11.26665372 -0.78372848
O -6.53256968 10.46693586 -3.22290224
O -5.56381472 9.69389357 0.61729905
O -8.36655799 9.76938263 -0.10288899
C -8.90267268 10.86635140 -2.79984380
H -8.71454864 11.90018067 -2.60784077
H -9.72858740 10.54498701 -2.20802438
O -9.20429830 10.68541419 -4.18551448
H -8.46665363 10.98542331 -4.71919452
H -9.17399192 10.26804893 -0.26957573
H -5.39756593 10.62148689 0.73301079
O -4.05417354 9.58839301 -3.16755348
O -3.70377791 9.16457303 -1.47569403
H -3.58492919 9.53697555 -3.89463091
H -2.87727273 9.25288215 -2.08709783
B -1.71685742 8.59334576 -4.26508851
O -2.97405212 9.47014766 -4.68353092
H -3.33306313 9.06071177 -5.47655795
O -0.37714720 8.54894999 -5.03191713
H 0.22561508 7.94829750 -4.59308374
O -2.00900133 9.22803064 -2.58256445
H -1.38453846 8.69191602 -2.08439557
O -2.24696092 7.14354050 -4.13098207
H -1.61273913 6.59985936 -3.63238399
H -2.36881319 6.77772795 -5.00860295
And output file terminates as....
End of file reading connectivity.
Error termination via Lnk1e in /usr/local/g09_b01/g09/l101.exe
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remove geom=connectivity keyword. And also don't forget to leave a blank line after the coordinates
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I need to know the origin/root cause of the CEE.
e.g. We know that one of the causes is  imperfect channel estimation. But I want to know what are the factors that lead to this imperfect channel estimation.
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In addition to Carlos' answer, I would add:
- channel frequecny offset,
- Doppler effect,
- time synchronization mismatch
among other sources of distortion. More specifically to channel estimation in multicarrier systems, in the case of scattered pilots, interpolation along time and frequency axes is required to estimate the channel over all the carriers/symbols. Most of interpolation methods induce estimation errors as well.
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How to model the spikes and discontinuities of the power spectrum's of the received signals ?
I am asking about models of spikes and discontinuities of the power spectrum of the received signals ? in radio-communication field ?
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You might add the random sine waves in the time sequence.
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How can we perform GenOsc fitting in ellipsometer for P3HT:PCBM organic films coated on glass?
First, I fitted using cauchy model in transparent region and got some thickness around 30nm. Later I unfit the thickness parameter when I parameterize to Bspline, now I find problem with the usage of GenOsc to get exact thickness when I do fitting finally.
Kindly somebody help me by telling the procedure how to do it.
Thanks in advance.
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I think they have a batch fit option (using the thickness in the transparent area) which convert the ellipsometric parameters into optical properties.
But if you want to fit both (thickness and optical properties) you have to biult a new material with more than one Oscillator (two in the visible range and one in the UV-range).
Or have a look at this paper
Annealing of P3HT:PCBM Blend Film—The Effect on Its Optical Properties, Ng Annie et al.
Best regards
Christian
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hi all 
How can i use GPU as co processor for CPU in guassain 
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Dear Hasan,
The only news about the implementation of CUDA in gaussian is that should be able in next version of gaussian or at least, that they are working with it. For a moment, with gaussian 09, you can not use GPU.
Even so, the gamess program has a version for linux where the CUDA is implemented. Also there are an other few programs that has this implementation.
In the link you will find a pdf with all programs that support CUDA. If you search gaussian, you will see that is under development yet.
I hope it helps you,
Joaquim Rius
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As the models used in Kalman filtering are also Gaussian processes, one would expect that there would be a connection between GP regression and Kalman filtering. If so, could one claim that GP regression is more general than Kalman filtering? In that case, aside from computational efficiency, what would be the other advantages of using Kalman filtering?
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Thank you Rolf and Paresh for your useful comments.
I read the references that you have cited. However, I am still not sure if these references fully answer my questions. So let me rephrase my questions.
Kalman filter recursively produces estimates of unknown variables based on system’s dynamics model, known control inputs to the system and multiple sequential measurements.
In Gaussian process regression, same process can be implemented in order to estimate the unknown variables. The system dynamics can be implemented in the form of Gaussian kernel and hence incorporated in the covariance matrix. The inputs and sequential measurements are then through use of the Bayes rule can be used to estimate the unknown variables.
My question is the following. Is there any problem that can be solved by kalman filtering which cannot be solved by Gaussian process regression? In this relation, I am not thinking about computational efficiency but on if, kalman filtering can offer insights, which are not already offered by the Gaussian process regression.
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I am trying to optimize a Eu3+ complex by DFT using gaussian09. I am currently using Ub3lyp and Gen (with 6-31g for common atoms and MWB28 for Eu). The calculations has been running for a week and I still haven't completed the first cycle (only 70 iterations done...). Does anyone have a better optimization sequence?
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It looks like the starting geometry is not too good, and gaussian has problems with even converging the first cycle. There are some usualt steps in gaussian that can be followed (listed below). 
First, though, optimizing ions is hard and the higher/lower the charge, the harder it gets. An Eu complex with the total charge od 3+ is in many cases not a realistic system, since there are almost always some counterions present and these could (and should) be also added to the system. Also, when optimizing ions make sure that you're using at least one + function in the basis set. (If this is an Eu(III) complex that is neutral, disregard this part).
Thing that help in convergence:
SCF=QC
SCF=XQC
FOr DFT make sure that you also have Int=UltraFine.
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I' m doing an embedded cluster calculation in which I have to fix the positions of some atoms and to add point charges with Gaussian09 program. this is my input file :
#P PBE1PBE/gen opt=modred nosymm scf=xqc freq pseudo=read Charge
and after the cartesian atomic coordinates, I specified the atoms that I want to freeze.
the calculation ends with this error "Cannot AddRedundant with Cartesian or Z-matrix opts.".
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thanks a lot. I will.
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I've always heard that you need to take at least *30* samples, to be "sure" that you have an exact enough mean and deviation estimates. I think this number comes from considering the central limit theorem to approximate your experimental results distribution with a gaussian, so that confidence intervals are easier to calculate. But I have never seen a formal proof or justification of some sort that after 30 samples the gaussian approximation is qualitatively better than before 30 samples. What is the rationale behind this number?
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I had the same question some years ago and I learnt that I (like many others) had been misinterpreting this. It's not that "30 in a sample group should be enough" for a study. It's that you need at least 30 before you can reasonably expect an analysis based upon the normal distribution (i.e. z test) to be valid. That is it represents a threshold above which the sample size is no longer considered "small". It seems to have little to do with power, which will depend on the usual factors of alpha, beta, delta and how much funding you have (:-)). I was going through some of my old notes and came across a plot I had printed of the difference between the square roots of 1/n and 1/n-1. At about 30 (actually between 32 and 33) this difference becomes less than 0.001, so Paul's comment seems to have an intuitive sense to it. I made a few notes about Bernoulli tests and the central limit theorem but the Chebyshev inequality was obviously a bridge too far and I seem to have abandoned the project at that point.
I am an anaesthesiologist, not a statistician and my knowledge of maths is limited but I learnt that in medicine the "30 should be enough" approach is invariably wrong and Charles is quite correct - do a full power analysis!
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sorry I do not have the expertise to answer this question.
Regards
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I have been trying to link tungsten complex transition states, and can't get any of my IRC jobs to work. I have been comparing my input to other IRC jobs and cannot find any error, yet every time I try and run the job, I get the same error.The error message I keep receiving is:  
IRC-IRC-IRC-IRC-IRC-IRC-IRC-IRC-IRC-IRC-IRC-IRC-IRC-IRC-IRC-IRC-IRC-IRC
Reading IRC summary table definitions from the input file.
DfStat: QParse returned with an error. IStat= -1
QPErr --- A syntax error was detected in the input line.
W 0
'
Last state= ""
TCursr= 122 LCursr= 0
Parse error in Link 123.
Error termination via Lnk1e in /usr/local/gaussian/g09D01/g09/l123.exe at Mon Jun 29 15:07:53 2015.
Job cpu time: 0 days 0 hours 0 minutes 3.4 seconds.
I will also attach my input. Any help would be much appreciated! Thank you in advance! 
Chris Shepard
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Thank you!
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Is there any other models for Laser distribution and moreover how to model Infocused(Focus of Laser just Inside the Powder Layer) and Outfocused(Focus of Layer just on top of the powder layet) Gaussian Laser Beam
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I think that for your purpose you can chose the simplest function that resembles the irradiance distribution in your laser beam. For example, some lasers (specially after propagation through a multimode fiber) may deliver a cross section distribution of the laser irradiance close to so called "tophat", which is roughly a uniform distribution in a finite diameter.
For the out of focus Gaussian beam, I just would calculate the beam diameter at the surface of the powder layer taking into account the focusing length, position of focus and beam waste. You may use gaussian beam propagation theory or can approximate it using geometric optics. Once you have the beam diameter at the surface of the layer, you simply model it as a gaussian beam with said diameter.
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I expect to get some nice figure where the uncertainty of unknown data points would be big and around sampled data points small. I got an odd figure and even odder is that the uncertainty around sampled data points is bigger than on the rest. Can someone explain to me what I am doing wrong? Thanks!!
Here is the code:
% Data generating function
fh = @(x)(2*cos(2*pi*x/10).*x);
% range
x = -5:0.01:5;
N = length(x);
% Sampled data points from the generating function
M = 50;
selection = boolean(zeros(N,1));
j = randsample(N, M);
% mark them
selection(j) = 1;
Xa = x(j);
% compute the function and extract mean
f = fh(Xa) - mean(fh(Xa));
sigma2 = 1;
% computing the interpolation using all x's
% It is expected that for points used to build the GP cov. matrix, the
% uncertainty is reduced...
K = squareform(pdist(x'));
K = exp(-(0.5*K.^2)/sigma2);
% upper left corner of K
Kaa = K(selection,selection);
% lower right corner of K
Kbb = K(~selection,~selection);
% upper right corner of K
Kab = K(selection,~selection);
% mean of posterior
m = Kab'*inv(Kaa+0.001*eye(M))*f';
% cov. matrix of posterior
D = Kbb - Kab'*inv(Kaa + 0.001*eye(M))*Kab;
% sampling M functions from from GP
[A,B,C] = svd(Kaa);
F0 = A*sqrt(B)*randn(M,M);
% mean from GP using sampled points
F0m = mean(F0,2);
F0d = std(F0,0,2);
%%
% put together data and estimation
F = zeros(N,1);
S = zeros(N,1);
F(selection) = f' + F0m;
S(selection) = F0d;
% sampling M function from posterior
[A,B,C] = svd(D);
a = A*sqrt(B)*randn(N-M,M);
% mean from posterior GPs
Fm = m + mean(a,2);
Fmd = std(a,0,2);
F(~selection) = Fm;
S(~selection) = Fmd;
%%
figure;
% show what we got...
plot(x, F, ':r', x, F-2*S, ':b', x, F+2*S, ':b'), grid on;
hold on;
% show points we got
plot(Xa, f, 'Ok');
% show the whole curve
plot(x, fh(x)-mean(fh(x)), 'k');
grid on;
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Dear Marcelo,
you are not doing anything wrong, the problem is that you want to plot some polygon with more change with the simple one! it's obvious this would happen.
you must use these simple codes in fist of every matlab code:
close all %close other programs
clear all %empty workspace
clc %clear the command window
you are doing great
regards
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I am doing a theoretical study about the catalytic activity of some structures using the software Gausian 09W. I ran the opt and TD-DFT calculation of each structure and got the band gap energy and the excitation energy of these structures. So, I would want to know if is the excitation energy or the band gap energy that I have to analyse to define the best catalyst.
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Dear Elder,
While excitation energy indicates the energy required for excitation between any two arbitrary energy levels provided that selection rules are not violated, the band gap energy is the energy required for excitation from HOMO (the highest occupied molecular orbital) into LUMO (the lowest unoccupied molecular orbital).
Best,
Saeed
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Will DFT B3LYP give a solution?
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Thank you very much.
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A well-known theorem in probability states: Let x be an Nx1 Gaussian vector with mean vector m and covariance matrix Cx .If we linearly transform x as y=Px using a square NxN transform matrix P, then y is also Gaussian with mean vector Pm and covariance matrix Cy=PCxPT.
This theorem has an elegant proof using the multivariate Gaussian probability density function (pdf).
It is also known that the above theorem is also valid for non-square (NxM) transform matrices, P
Does anyone know any reference book containing the proof for the more general case of non-square linear transformations?
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(Actually, Jet Propulsion Laboratory)
Try this approach.
Definition: the scalar random variable x is Gaussian if either x has a Gaussian density or x is a constant.
Definition: the random N-vector x is Gaussian if, for any constant N-vector a, a'x is a Gaussian random variable.
As a consequence, each component x(i) of a Gaussian random vector x is a Gaussian random variable, and so Ex and cov x := E(x-Ex)(x-Ex)' exist.
Let x be a Gaussian vector. Let y = Px for some M x N matrix P. For any M-vector b, b'y = (b'P)x, which by definition is a Gaussian random variable. Therefore y is a Gaussian M-vector, and
Ey = P(Ex),
cov y = E(y - Ey)(y - Ey)' = PE(x - Ex)(x - Ex)'P' = P(cov x)P'
See Rosenblatt, Random Processes, Oxford U. Press.
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Here i have attached a file which shows the anharmonic correction option available in Gaussian 09W. But i don't know How do we use the option "anharmonic corrections" in Gaussian 09W? 
hoping to hear back from any one soon.
Thank you in advance.
by
T.Karthick
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to add keyword freq= anharmonic
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Vortex beam is produced by spiral phase plate in STED microscopy, for example. What is the nature of its polarization? radial? azimuth? or mixed of both (spiral)? does it depend on input polarization?. Can linearly polarized vortex beam exist as center is always zero? 
Thanks
Mahendar
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In principle the polarisation structure of a beam can be set independently of the spatial structure of the intensity.   For example if a linearly polarised Gaussian beam illuminates a forked diffraction grating then the results vortex beam (in the first diffractive order) is still linearly polarised.  For example, the beams made by Marat Soskin and other.   These beams can be described as scalar beams where at every position in the beam one can express both a complex amplitude and a polarisation state.  
Alternatively one can create "vector" beams where the polarisation structure itself maps to the field.  Eg a radially polarised beam with a zero on-axis intensity. For example, the beams made by Gerd Leuchs and others.
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How to select Restricted, Unrestricted and open shell in gaussian calculation ?  what is it mean? and how to calculate it or select it in our case ?
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Dear Paras,
what system do you wish to consider? And what approach do you want to use for it? In the case of Hartree-Fock approach, you can use the following keywords:
HF - for Restricted close-shell system (all orbitals are considered as doubly occupied);
ROHF - for Restricted Open Shell system;
UHF - for Unrestricted approach (all alpha- and beta-electrons are treated separately, and alpha- and beta orbitals are considered as singly occupied).
The table in the file attached illustrates all these concepts really nice:
Best regards,
Aleksey.
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Dear all,
I want define a periodic slab in xy plane, and my slab has the net dipole,
considering the intrinsic problems by  using the dipole correction, I prefer have the finite structure in z-direction (no vacuum definition)
which theory and codes could be helpful to do this? 
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Dear Yavar,
Thank you very much - work functions of covered surfaces is indeed another application I didn't realize that a slab-gap may lead to an unrealistic results. I guess building a centrosymmetric slab with adsorbates on both sides may not fully capture the effect surface polarization may have on the work function.
I have been running a few calculations on self-assembled mono-layers on Au(111) with our periodic DFT code in 2D pbc. In that case the work function should just correspond to the Fermi level, having a proper vacuum. This is an added advantage to 3D pw codes where you need to reference against the potential in the middle of your 'vacuum' gap. I'm not sure if this also holds true for semiconductors, being a chemist I would need to check with our physicists developers here.
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Dear All,
In a Deterministic Framework where we have the following Linear Model:
y(t) = H.x(t) + n(t)
where
y(t) is the observed vector of size Nx1 (we have T observations)
H is an NxP matrix (no constraint on P, P could be smaller or larger than N)
x(t) is a Px1 vector
n(t) is random noise.
It is well known that if n(t) is a Gaussian process, then you couldn't do any better than Max Likelihood, i.e. the L2 norm is optimal to estimate parameters in H and x(t). 
My question is : when does ML become sub-optimal ? 
Thanks.
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if P is larger than N, I am not sure that the ML is still optimal because the Hessian matrix of the Likelihood Function could no more be definite positive, hence some variances of the estimated x() might become infinite
if P is less than N, the ML is definetely optimal with regard to bias and the variance of the estimated parameters, but if that is valid for estimation, it is not for prediction.
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What differentiates full and reduced integration for a solid brick element? I know that only one Gauss point exists in the middle of the element for a reduced integration, but what decides whether a solid element is fully integrated?
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The full integration for a 8-node solid brick element is a 8-point scheme. But for incompressible or nearly incompressible behaviors (as for von Mises elastoplasticity), locking phenomena can appear when using such elements. These locking phenomena appear when the displacement approximation is not sufficiently rich to satisfy both the momentum balance and the incompressibility equation. To avoid this problem, one way is to use reduced or selective integration techniques. 
For the reduced integration technique, the incompressibility condition and the momentum balance are computed by means of only one integration point but this leads to the possible non unicity of the solution in static analyses or to the well-known hourglass phenomena for time dependent problems. Despite of this difficulty, this approach is very efficient for explicit dynamic simulations because calculation time is directly linked to the number of integration points. But in this case, hourglass modes must be controlled.
The selective integration technique consists in using the 8 integration points but with a volume change constant over the element. The volume change can therefore be calculated either at only one integration point (in fact at the element center) or as the mean value of the volume change over the element (B-bar method).