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First-principles Calculations - Science topic
Explore the latest questions and answers in First-principles Calculations, and find First-principles Calculations experts.
Questions related to First-principles Calculations
In first principles calculations, are functionals with the same name used in different computational software the same? For example, the GGA-PBE functional in VASP software and the GGA-PBE functional in CASTEP module?
Hi! I am an independent researcher interested in Li-ion battery electrodes, particularly in their first-principles calculations. I understand the basic theory of DFT and crystals, but I am extremely new to the field. I am following the methods outlined in this paper: , where we first perform DFT calculations on different Li vacancy orderings, then construct the convex hull and voltage vs. composition graph. After that, we perform cluster expansion and Monte Carlo simulations to determine the thermodynamic properties and kinetics (for diffusion). However, I am having a hard time finding the necessary resources to learn how to perform these calculations.
First, I would like to ask if there are any resources available where I can practically learn how to conduct these calculations?
Next, I do not own a license for VASP, so I am using Quantum Espresso instead. From what I understand, we need a crystal structure and can then perform the DFT calculations on it. My question is: Do we need to know the exact crystal structure, such as the specific locations of the Li ions, etc.? I am planning to study organic electrodes, for which crystal structures are relatively scarce.
Also, how do we change the Li-ion vacancy ordering? How many unit cells in a supercell are necessary?
I think those are all the questions I have for now. Thank you!
Hi, folks!
I am studying the hyperpolarizability of a crystal using DFT calculations. I learned that Gaussian code is able to do that with POLAR keyword in the input file. As Gaussian is not professional at dealing with periodic structures, I abandoned the crystal box and took out the coordinates of its unit cell as well as 1*1*2,1*2*1, 2*1*1, 1*1*3 supercells for input structures of Gaussian. The calculations are performed at CAM-B3LYP/6-311++g(d,p) level. Below are some results of total beta in the unit of 10^-30 esu.
1*1*1: 33
1*1*2: 97
1*2*1: 78
2*1*1: 53
1*1*3: 199
As can been see, these values diff largely and do show any convergence. What is the correct way to simulate the crystal? How large size of crystal structure should be used?
Thank you very much in advance!
Hi RG Community,
While running wannier90.x to compute the MLWFs, I encountered the following error:
------------------------------------------------------------------------------
Cycle: 1
wann_main: ZHEEV in internal_new_u_and_m failed, info= 151
trying Schur decomposition instead
wann_main: SCHUR failed, info= 152
Exiting.......
wann_main: problem computing schur form 1
------------------------------------------------------------------------------
I have already performed the sequence: SCF, NSCF, wannier90.x -pp, and pw2wannier90.x. The problem arises during the wannier90.x calculation.
Does anyone know how to resolve this issue?
Thank you in advance for your help!
Rgds,
Gabriel Vinicius
Hi, I'm trying on adsorbing molecules (which are used as organic electrolytes for Li-ion batteries) onto the Cu(111) surface. I want to visualize the charge distribution between the molecule and the surface, so I'm calculating the charge density difference using VASPkit.
However, even though only the adsorbate was changed, the minimum and maximum values of the isosurface F varied. This makes it difficult to compare the structures in VESTA using the same isosurface settings.
So, my question is ..
1) How can I adjust the isosurface range manually?
2) Which tags in INCAR should be adjusted?
Here's my INCAR tag. for all system I used this INCAR tag. (For single point calculations)
LCHARG = .TRUE.
LREAL = AUTO
NELM = 120
ENCUT = 520
ALGO = Normal
EDIFF = 1E-05
#EDIFFG = -0.02
ISPIN = 2
IBRION = 2
NSW = 0
ISIF = 2
ISMEAR = 0
SIGMA = 0.02
ISYM = 0
Thanks.
Correcting cellular growth errors. https://www.researchgate.net/publication/382049802_Correcting_Cell_Errors
I am doing some first-principle calculations on the thin film system like NiO/Ag(001). Now I need to calculate the surface energies of the system. What will be the formula for that and how I should proceed?
I was trying to calculate dielectric constant of TiN. I did self-consistent calculation first and then run the calculation of dielectric constant with INCAR like this:
PREC = Accurate
ALGO =VeryFast
ISPIN = 2
ISMEAR = 0
SIGMA = 0.1
NSW=0
NELM=160
NELMIN = 6
IBRION = 8
ENCUT = 520
AMIX=0.02
BMIX=0.0001
EDIFFG=-0.01
EDIFF=1E-7
NCORE=1
POTIM = 0.1
LWAVE=.T.
LCHARG=.T.
ISIF=2
LREAL= Auto
LEPSILON = .TRUE.
LPEAD = .TRUE.
MAGMOM = 216*1.0
However, I always get this error:
Linear response reoptimize wavefunctions to high precision
DAV: 1 -0.208534475583E+04 0.16173E-06 -0.89612E-06 16800 0.597E-04
DAV: 2 -0.208534445618E+04 0.29965E-03 0.30306E-03 13920 0.161E-04
DAV: 3 -0.208534479076E+04 -0.33458E-03 -0.28065E-03 15264 0.378E-03
Linear response to external field (no local field effect), progress :
Direction: 1
N E dE d eps ncg rms rms(c)
RMM: 1 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
RMM: 2 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
RMM: 3 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
RMM: 4 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
RMM: 5 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
RMM: 6 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
change of polarisation eV/A/(eV/A) component 1 : 0.000 0.000 0.000
dielectric tensor component 1 : 1.000 0.000 0.000
Linear response to external field (no local field effect), progress :
Direction: 2
N E dE d eps ncg rms rms(c)
RMM: 1 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
RMM: 2 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
RMM: 3 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
RMM: 4 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
RMM: 5 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
RMM: 6 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
change of polarisation eV/A/(eV/A) component 2 : 0.000 0.000 0.000
dielectric tensor component 2 : 0.000 1.000 0.000
Linear response to external field (no local field effect), progress :
Direction: 3
N E dE d eps ncg rms rms(c)
RMM: 1 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
RMM: 2 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
RMM: 3 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
RMM: 4 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
RMM: 5 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
RMM: 6 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
change of polarisation eV/A/(eV/A) component 3 : 0.000 0.000 0.000
dielectric tensor component 3 : 0.000 0.000 1.000
Linear response to external field, progress :
Direction: 1
N E dE d eps ncg rms rms(c)
RMM: 1 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00
RMM: 2 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00 0.000E+00
RMM: 3 0.000000000000E+00 0.00000E+00 0.00000E+00 0 0.000E+00 0.000E+00
vasp_std:243338 terminated with signal 11 at PC=72fc0e SP=7ffec5d89a70. Backtrace:
/project/def-jsong/share/vasp.6.1.1/bin/vasp_std[0x410e12]
/cvmfs/soft.computecanada.ca/nix/store/63pk88rnmkzjblpxydvrmskkc8ci7cx6-glibc-2.24/lib/libc.so.6(__libc_start_main+0xf0)[0x2b3ff97572e0]
/project/def-jsong/share/vasp.6.1.1/bin/vasp_std[0x410d2a]
srun: error: bc11628: task 55: Exited with exit code 1
I think it starts to calculate, but somehow always stop due to some errors.
My TiN structure has 216 atoms in total.
Can someone help me with this error?
Thank you so much.
I want to make a hetrostucture in material studio for VASP calculations. But i am facing difficulty while doing this. Your suggestion and guideline would be highly appreciated.
I can not able to figure out which orbital(px,py,pz etc) corresponds to each column in VASP output file DOSCAR
Hello Superiors,
I need yours expertise and kind help on using kdotp-symmetry package (weblink is attached). I am trying to generate k.p Hamiltonian using kdotp-symmetry. But I am unable to do it using this package. I need some kind helps to use and run kdotp-symmetry.
I request your helps/suggestions on running kdotp-symmetry. Your any help will be highly appreciated. Thanks in advance.
Thanks and Best Wishes
Chanchal K Barman
I want to calculate the piezoelectric properties and I want to know what is the best software to do this. I am currently using wien2k, but if there are other software better than this, please mention them.
I am beginner to use VASP. I want to learn how to make doping of different compounds as a function of some elements to calculate different electronic and magnetic properties.
I usually get POSCAR from materials project. But this time the combination of alloys I need is not available in that database. So i want to know, How to prepare POSCAR file of four element FCC alloy for VASP calculations?
Dear All,
Could you please suggest a good source materials (e.g., books, publications, ppt.....etc.) on the usage of first principles calculations in studying equilibrium isotope fractionation.
Thanks and Regards,
Ahmed
I need this file to do my first principle calculations.
I want to calculate the phonon thermal conductivity and for this purpose, I require the third-order IFC. If is there any software to calculate the 3rd order IFC using first-principles calculations.
I work on first-principles calculations of DMSs, where I substitute one cation with a 3d transition metal element in a host semiconductor, I plotted the Projected bandstructure and projected density of states (DOSs) of my compound.
- How can I determine from these plots the type of exchange interaction ( double exchange, p-d exchange, anti-ferromagnetic or ferromagnetic superexchange, RKKY exchange )?
I see the paper: J.Phys.:Condens.Matter19(2007)436227
What I have understood is :
- When the broadening of impurity 3d bands around Fermi level (Ef) is partially occupied and situated above p anion states of the host semiconductor, resulting in double exchange interaction.
- The presence of 3d states below the p anion states in the upper part of the valence band (VB) resulting in p-d exchange interaction.
- some compounds have both double and p-d exchange interactions.
- some compounds can have a competition of double and superexchange interaction depending on the position of Ef in top 3d bands.
- In the anti-ferromagnetic superexchange interaction, we need two impurities in the system with anti-parallel aligned and having equal concentrations of c/2, the electronic states with the same spin direction hybridize with each other.
But I am still confused about Superexchange anti-ferromagnetic and ferromagnetic.
- Is needed two 3d impurities in the studied compounds? or can occur by the presence of one impurity in the unit Cell?
- For the ferromagnetic superexchange interaction, is needed to two impurities in both of them Fermi level falls between eg and t2g states of majority (or minority) spin channel? How occupied and empty states in the same spin channel can hybridize with each other?
- How can I determine RKKY interaction from DOSs?
- What is the intra-atomic exchange constant J_H? how can calculate? and how it can help to determine is strong or week?
Thank you in advance.
Among the first-principles calculation methods, is there a mechanical calculation method suitable for amorphous structures? That is to say, the spatial symmetry of the structure is not required to simplify the calculation
It is easy to perform calculations for compounds with known structures. But if we need to substitute other atoms reducing the content of one atom, it becomes hard for me to relax that structure. As I am a beginner for theoretical studies using QE codes with little experience, I welcome it if anyone can collaborate to work on it with me or at least can show me the right way to perform it.
There are large volume of handbooks that prescribe suitable etchant for a particular metal or ceramic, But their theoretical justification is hardly ever mentioned. Then, is it possible to estimate (at least a first order approximation) composition of etchant for a metal/alloy (if its chemical constituents and possible present phases are known from standard thermodynamics and metallurgy) , solely from knowledge of organic and inorganic chemistry? Or just is it purely empirical trial-and error?
For example, nital or picral are good etchant for some ferrous alloys, but why is the acid nitric acid (cannot be sulfuric/hydrochloric/phosphoric?) instead of other strong acids; or picric acid instead of any other aromatic ortho-para trisubstituted (electron-withdrawing group) phenol? Is there any aromatic coordination chemistry or organometallic chemistry involved? Why is the other reagent alcohol instead of , say, water/ketone/aldehyde/ether; and why is the alcohol ethanol instead of, say, methanol, isopropanol or neopentanol?
Similar question can be posed for any other metal/alloy system and corresponding etchant. Exact metal or etchant are not asked here. And some related questions that may rise are
Is reactivity of particular metal contained in a microstructural phase with inorganic and organic reagents cannot be even first-order estimated with standard inorganic and organic chemistry? Why?
If coloring compound formation is the key, then how the color between transitional/ non-transitional metal and a ligand (can be organic chromophore) can be estimated with relatively simple first principle study?
Hi, everyone. So often I took the Fermi velocities of metals from Ashcroft and Mermin's book (http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/fermi.html#c1). For example, the values of vf for Ag, Au, and Cu are 1.39E+06 m/s, 1.40E+06 m/s, and 1.57E+06m/s, respectively. However, in a recent literature, these values are given as 1.448E+06 m/s, 1.382E+06 m/s, and 1.109E+06 m/s from first principle calculations ( ). Especially, the difference between the two dataset is quite large for Cu. Should I take the recent data?
Is there any way to find out parity from the band structure of First principle calculation ?
Any kind of help will be appreciate.
Thanks
I changed some of the Sn atoms' composition to 50%Sn and 50%Sb in the Co2TiSn system. I checked spin-polarized and use formal spin as initial to calculate the ferromagnetic system. However, the software told me that
Cannot run CASTEP for the given scope(disordered crystal).
The following features are not supplied:
Use of formal spin
How can I avoid this error?
I want to investigate the Fermi surface nesting condition from the calculated bare susceptibility using quantum espresso.
Hello everyone, so my system has 6 different atoms in the simulation cell and the total number of atoms is equal to 14 atoms. I am Phono3py to create the displaced POSCAR files to calculate the harmonic and anharmonic force constants. But theproblem I am facing is that, Phono3py creates 5000+ input files for anharmonic calculations. So, I wanted to ask is there a way to reduce the number of simulations and still get an accuracy in the calculation of thermal conductivity. I am using VASP to do the DFT calculations.
Hi All
I am doing phonon calculation of adsorbate surface using supercell DFPT (IBRION=8) method. During completion of total degree of freedom 192,
after 133/192 degree of freedom energy is going to be positive like
Linear response progress:
Degree of freedom: 133/192
N E dE d eps ncg
rms rms(c)
RMM: 1 0.217378571184E+00 0.21738E+00 0.19116E+02 5386
0.343E+01
RMM: 2 0.127254148439E+00 -0.90124E-01 -0.55512E-02 8094
0.438E-01 0.322E-01
RMM: 3 0.124590051032E+00 -0.26641E-02 -0.16976E-02 11623
0.162E-01 0.602E-01
RMM: 4 0.125935957234E+00 0.13459E-02 -0.39499E-03 8126
0.103E-01 0.490E-01
RMM: 5 0.123635491638E+00 -0.23005E-02 -0.39546E-03 9713
0.765E-02 0.601E-01
RMM: 6 0.121118955639E+00 -0.25165E-02 -0.38393E-03 9767
0.453E-02 0.743E-01
RMM: 7 0.125200747539E+00 0.40818E-02 -0.44584E-03 8647
0.634E-02 0.253E-01
RMM: 8 0.127131220393E+00 0.19305E-02 -0.45986E-04 7966
0.449E-02 0.186E-01
RMM: 9 0.127249394402E+00 0.11817E-03 -0.23046E-04 8953
0.247E-02 0.142E-01
RMM: 10 0.127427043358E+00 0.17765E-03 -0.40435E-05 8644
0.178E-02 0.379E-02
RMM: 11 0.127451795033E+00 0.24752E-04 -0.11972E-05 9286
0.922E-03 0.425E-02
RMM: 12 0.127439216517E+00 -0.12579E-04 0.95608E-06 7792
0.606E-03 0.138E-02
RMM: 13 0.127433858265E+00 -0.53583E-05 0.11061E-05 9347
0.344E-03 0.164E-02
RMM: 14 0.127440025812E+00 0.61675E-05 0.14637E-05 8767
0.248E-03 0.474E-03
RMM: 15 0.127441655698E+00 0.16299E-05 0.16395E-05 9768
0.141E-03 0.593E-03
RMM: 16 0.127442586932E+00 0.93123E-06 0.15813E-05 9059
0.981E-04 0.249E-03
RMM: 17 0.127444457475E+00 0.18705E-05 0.14892E-05 10340
0.592E-04 0.202E-03
Why is this so ? How to resolve this problem ?
For My other bulk system 2*2*1 supercell (96 atoms)I am getting negative
frequecies. I read it shows instability of system at 0K. If after possible
improvement in calculation negative frequencies still remains then what
should we do for confirming instability of system at 0K. Does people
report negative frequencies in phonon DOS ?
How does resolve negative frequencies? I have attached here my phonon DOS.
Thank You All
Dear all,
1) I am trying to calculate the elastic constants (C2D) of a 2D material by the fitting of a quadratic polynomial to a curve of energy difference (Eequ - Estr) versus strain. As suggested in several studies (E.g. ), if I fit my curve to y = ax2 + bx + c, my elastic constant along x should be 2a/V0 (through the double differentiation of y w.r.to x, V0 is the volume at equilibrium). Is this correct? In some articles, I found the plots and calculated values are not in agreement although they mentioned a similar approach. And simply, V0 = a1 * a2 in 2D. Is not it correct?
2) Also, I am trying to calculate the effective mass (m*) using a commonly known formula: m* = ℏ2/(∂2E / ∂k2). Here if I fit my conduction band minima (CBM) [or valence band maxima (VBM)] curve to y = ax2 + bx + c, and take the double differentiation of y w.r.to x, it gives rise to ∂2E / ∂k2. Is it correct? And how can I calculate m* in the unit Kg (or as the product of me), my E is in eV?
Please let me know if there are any journals/discussions related to the above queries.
Best,
Abhiyan Pandit
University of Arkansas
Dear all,
I have several questions regarding the calculation of embedding energy of the EAM (Embedded Atom Method potential) potential type. In the paper of "Phase stability in the Fe-Ni system: Investigation by first-principles calculations and atomistic simulations (as attached)", it is stated that the embedding energy is calculated by inverting the universal equation of state (equation 9 in the attached paper). I have three questions regarding this calculation:
(1) This universal equation of state (equation 9) is independent of host electron density, but an equation of cubic lattice constant a, while the embedding energy F should be an equation of host electron density (\rho). Then how the equation 9 relates to the host electron density (i.e., sum of all electron density induced by all other atoms)? How to calculate the host electron density from single electron density, since we do not know the number of atoms?
(2) How the equilibrium atomic volume Omega0 is calculated? Using 4/3*pi*r^3 (r is the atomic radius = sqrt(2)a/4 in fcc lattice), or a0^3/4 (a0 is the equilibrium value of a in equation 9, this is from the paper: Atomistic modeling of the γ and γ'-phases of the Ni–Al system)?
(3) What does the "inverting" mean here? The embedding energy = 1 / EOS (equation of state)?
I am Masters student with specialization in Battery Field and Simulations. I want to know how to start studying First Principle calculation and how to perform first principle calculations using VASP.
I am focused to study the role of phononic mismatch in the thermal conductivity of two layers interfacing with each other. what will be the most simple method for calculation of thermal conductivity using first-principle calculations?
I have run boltztrap calculations. And i have case.trace file with 10 columns in total. Now I need to plot electrical, thermal conductivities Vs Temprature.
I use to plot with Gnuplot, but when i use :
-> plot 'case.trace' u 2:8 w l
i got a lot of curves in the figure...
here attached my case.trace file.
Could you please tell me the procedure of plotting them with gnuplot?
A-0 0 0
B 0.5 0.5 0.5
C 0.5 0.5 0.5
O 0.5 0.0 0.5
O 0.5 0.5 0.0
O 0.. 0.5 0.5
I want a simple method for calculating electron-phonon coupling constant (approximately). Taking advantage of first-principles calculations, not the linear response theory. I hope to change the position of some atoms, calculate ground state energies and eigenvalues, and then estimate the electron-phonon coupling constants. I don't know whether it is feasible or not. Is there such a method?
I want to introduce two charged atom in a supercell using first principles calculation (such as ABINIT, VASP). Is it possible? If not, why?
My steps is as follows, is there something wrong?
1. create a MAX model-Ti2AlC (directly from database)
2. delete Al atoms from MAX model, obtain bare Ti2C
3. build surface (001), and get a monolayer Ti2C, then put 2 oxygen atoms on both sides.
4.perform structural optimization (only for atom positions)
Should i do structural optimaztion before building surface? Thanks for everyone's help.
I'm doing some work with GCMC, but a problem came up.
I want to pack all the residure space in porous material with metal.
(ex. Al, Zn, etc)
It was planed to model the situation of porous material filled fully with metal atoms, using the method like melted metal, ALD.. whatever.
But non-bond forcefield seems not to be appropriate for this purpose. And I'm suffering difficulty in searching for any forcefield of metallic bond.
Is there no way to do this? or shoud I have to do make the forcefield on my own using first principle calculation? Please give me some advice for the problem.
Dear VASP users,
I am plotting charge density 2D slice for LaVO4 system in VESTA, In 2D plot one scale bar comes in left side which is not showing any value in my case and what represent that ? How does mark corresponding element in 2D charge density plot as in attached paper for LaVO4.
Over all my query is that how does know which charge density is corresponding to which element in charge density plot and what represent scale bar in left side which is not showing any value. Any other software except VESTA for plotting CHGCAR file.
I have attached snapshot charge density plot for LaVO4 from attached paper like wise I want to plot charge density for my LaVO4 system.
I have also attached 001 2D plot for my LaVO4 system and related CHGCAR file.
Thank you for help and support !


I would like to find the k-points for Monoclinic system.
The path follows the trend like this
G-Y-M-C-E-M1-A-X-G-Z-D......etc.
In band structure calculations I have to give k points in this format..
12
G 0 0 0 10 ( this we know)
Y ? ? ? 10 (10 is the points b/w symmetry points )
M ? ? ? 10
C ? ? ? 10
....
..........
.....
My doubt is how to find the Y, M and C points.
Is there any software for all systems or website?
What is the dielectric constant value of alkaline solvent should be taken to investigate the dft first principle calculations using NWChem (COSMO function) or Gaussian?
Molecular dynamics/First principles calculations of glassy systems.
Thank you in advance,
CHAKER Ziyad
How to calculate bond strength using NWChem; like Wiberg bond indices are used to calculate bond strengths in Gaussian.
Recently, I've get through a system which has six internal degrees of freedom. I am not aware of internal structural parameters (internal degrees of freedom/free parameters). If it depends on the structure or a choice of lattice, how can i calculate it while doing first principle calculations using VASP code? Any suggestions will be appreciated..
Thank you
As deep learning, learning algorithm based on multilayer neural networks, which can figure out regularities in huge data (extracted from experiment), and express them in equations; is developing. How would this development affect computational physics? Will we still be using methods like first-principles calculation etc. as often?
Density functional theory , first principle calculations, condensed matter physics, material sciences
Dear experts,
I think that CaSiO3 has direct and indirect band gap. I am trying to know the direct and indirect band gaps of wollastonite( location of BZ point). A band gab of 5.022 eV at gamma (G) point according to LDA (castep code) ( is that direct or indirect band ). There is another interesting minimum conduction band at B point ( is it related to indirect band gap) with valence band minimum at C point . I really need to interpret the results shown in the figure below accurately. any help will be appreciated.
best regards
Dear researchers,
I would like to learn first principle calculation for First-principles study of structural, electronic, and optical properties of cubic III-IV semiconductor. Kindly suggest me good books to start with.
Thank You
I did a calculation based on VASP. The goal is to exact band structure from wannier90 package.
The initial projection for wannier90 is essential, so I used Random initial projections to obtain the wannier functions. But the following convergence of the “Wannierisation” procedure is rather harder. After 7000 iterations, the convergence window is still around 1.0E0.
I think the issue may comes from the initial projection. Then, I assigned the atoms the orbital projection for the initial projection. As a results the num_wann is not equal to num_bands, which is from NBANDS in VASP. However, the convergence of the “Wannierisation” procedure is difficult, too.
So I wander if anyone can offer me some tips? Thanks a lot!!
PS: the system contains 48 atoms, which presents NBANDS = 184 by default.
Hi, everyone! When I calculated the properties of two-layer or more 2D nanomaterials, whether I should constraint the atoms of lowest layer or not? and what way should i use, by the Fix Cartesian Position or Fix Fractional position?
I need a free software for Windows to perform conceptual DFT analysis like hardness, softness, philicities, and Fukui. Please if you know where I can download any good one left the link in the answer
Hello, researchers.
I'm now studying on the reactions between Al and Fe2O3 by first principle molecular dynamics. I have got the CHG file, then, how to export and display the charge density at different times?
Hope to get your help.
Thanks a lot!
Hello everyone
I want to do optimization of monoclinic structure with wien2k code. Please give me your suggestion how i can optimize monoclinic structure.
If we perform density functional theory (DFT) for any small system consisting of simple Lithium ion(s) under both generalised gradient approximation (GGA) and GGA+U (hubbard) term, in general, what would be the order of change in ground state energy between both the levels of theory?
i.e. the basis equations for geometry optimizations and energy calculations. The equations given for the energy in DFT in the turbomole manual are indeed very less. I need to know the equations in details.
I am trying to compute the concentration of complex defects using the paper from K. Biswas and S. Lany "Energetics of quaternary III-V alloys described by incorporation and clustering of impurities". (https://journals.aps.org/prb/abstract/10.1103/PhysRevB.80.115206)
If I understand correctly the method, I need to perform the following steps to get the concentration of a complex defect AB:
1) Compute the concentration of simple defects A and B and the concentration of the complex defect AB ;
2) Apply the double-counting correction to the concentrations;
3) Apply the normalisation correction to the concentrations
4) If the concentrations are consistent, stop the process, else, restart from step 2.
I tested this model on a defect with a negative binding energy and I observed that the simple defects concentrations increase with each step and the final result is non physical as I get a complex concentration higher than 1.
It would be of much help if anyone could point out where my error is.
Best regards,
Emmanuel
PS: I have attached a pdf file which shows the first iteration of my calculation if that can help to find my error.
Asking for a friend who doesn't currently have access to researchgate:
I am trying to simulate the optical properties of organic solar cells. i would like to know what functional would provide an accurate result for geometry optimisation of the lattice and optical properties calculation while also being computationally efficient.
I am a junior undergraduate, just finished Griffith's quantum mechanics, and also touched a little solid physics(First eight chapters of KITTEL).
I want to know how to calculate the electron distribution in the crystal of sodium chloride from the solution of the Schrodinger equation. If sodium chloride is too difficult, whether the sodium metal can be accurately determined.
I want to know where I can go to learn these things, and what books to read. Thank you!
when i use the quantum espresso to do the converge test for k points test of the scf for metal,but when it comes to calculate the 100 100 100 k points ,it gives a CRASH file :too many k points.as i know for the metal under the same smearing degauss,the number of k points is more ,the Fermi face is more clear in IBZ,but here it told me too many k points and make erro,why?thanx
I'm kind of a beginner so please if my question is so easy please excuse that.
I want to know how to model solid state systems. If you have for example a silicon unit cell.
What information do you need to know in order to model the system?
The cutoff energy and other information that is needed, can you explain that?
and what is the best solid state code?
Thanks
I have done vc-relax on a simple cubic structure with a=5.4799 having an initial atomic position as:
INITIAL
ATOMIC_POSITIONS Crystal
0.00 0.00 0.00
0.25 0.00 0.50, and obtained the final cell-parameters:
FINAL
CELL_PARAMETERS (alat= 5.47990000)
0.982742776 0.000000000 0.000000000
0.000000000 0.960295032 0.000000000
0.000000000 0.000000000 1.024602826
ATOMIC_POSITIONS (crystal)
-0.007496170 0.000000000 0.000000000
0.257496170 0.000000000 0.500000000.
Please, If I set ibrav=0, how can I obtain lattice parameter (a); and which of these atomic positions is suitable for use because I am just a novice in this field of study.
Thanks
Someone could give me a tutorial in VESTA that allows me to learn how I prepare a slab for DFT computation in order to simulate a surface calculation to see the atomic and electronic structure of surface.
This is my first attempt , please help.
Thanks in advance.
Hello,
I am running first principles calculations on indium gallium zinc oxide system. The average bond length value that I have obtained is 1.99 Å, whereas in literature, a similar calculation has resulted in average bond length value of 1.79 Å. Is this diifference significant?
Is there some literature available that contains some guidelines as to what the range of this variation should be.
Thanks,
Divya
Dear all,
I know there is a software called SRIM, which can calculate the dose depth profile. Also, the pre-irradiation and post-irradiation properties can be compared and evaluated by many experimental techniques such as nano-indentation, in situ X ray micro-diffraction, Tof-SIMS, SEM and TEM. In addition, first-principles simulation and kMC can be used to simulate the bulk and grain boundary diffusion of some fission products like Ag, Cs, Sr and Eu. What I would like to ask is, however, the kinetic process regarding the nuclear materials, for example the diffusion under irradiation. Does someone have relevant research experiences or can you recommend some references for me?
Any suggestions are appreciated.
Thanks in advance!
Topological insulator consists of bulk insulator state and surface metal state. When I obtain its effective dielectric constant (either experimental measurement or the first principle calculation), how to separate the contribution from bulk state and surface state? In the paper Nat Commun 2014, 5, 5139, the authors use Tauc-Lorentz formula and Drude formula to fit bulk and surface contribution, respectively. I am not clear how to involve the thickness of surface state in the fitting process. Can anyone help?
Thank you very much.
I have seen that there is significant difference between the total DOS of the system and PDOS of the system. The intensity of TDOS is found to be higher than the intensity of PDOS (after addition of projected density of states). Why?
Secondly, I have found that the magnetic moment in OSZICAR is not consistent with the value of magnetic moment given in the OUTCAR. The value of magnetic moment given in OSZICAR is always larger than that of OUTCAR. Why?
Thirdly, which value of magnetic moment is correct one?
Can we calculate magnetic moment from the difference of spin up and spin down DOS? If yes, then how can we calculate magnetic moment from DOS?
I have done elastic constant calculation using IBRION=6. I have used the following script (.pbs file). I got the output as SUMMARY.fcc. I have plotted the output as 1.tiff but I donot get the result as expected. I am confused how to proceed ahead. Kindly help me. I think there is problem in .pbs file.
Thanks
Dear Experts
Form results of BoltzTraP with no carrier concentration. Please help me to plot quantities such as Seebeck vs. carrier concentration. (case sample Si.trace)
1. What is SI unit of Number of carrier per unit cell volume?.
2. How to converse Number of carrier per unit cell volume to carrier concentration (in unit cm^3)?.
Best Regrads
Meena Rittiruam
Hello,
I'm studying the effect of varying the Li concentration in LixMn2O4 (x=0-1), I calculated the relax lattice constant and get acceptable results, but I haven't been able to calculate the intercalation voltage for different concentration of Li.
I'm using the following procedure:
V(x) ≈ - ΔE/(xj-xi)e (xj = 1, xi = 0)
ΔE = E[LixMn2O4] - E[Mn2O4] - E[Li]
E[ ] is energy/formula unit
I had tried without relax, relaxing each LixMn2O4 and Mn2O4 structures and also only relaxing LiMn2O4, but the results aren't congruent with previous publications.
I'm using as reference the paper
Factors affecting Li mobility in spinel LiMn2O4—A first-principles study by GGA and GGA+U methods, Bo Xu, Shirley Menga, Journal of Power Sources 195 (2010) 4971–4976
I'm using simulation package VASP and I'm doing GGA and GGA+U calculations
INCAR that I have used
- GGA relax calculation http://pastebin.com/NVs36wKu
- GGA energy calculation http://pastebin.com/j8ds3WVD
- GGA+U relax calcuation http://pastebin.com/k1UwmPqk
- GGA+U energy calcuation http://pastebin.com/bdd4Bu8e
Anyone has some experience with this types of calculations?
How can I get the voltage?