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# Computational Materials Science - Science topic

Explore the latest questions and answers in Computational Materials Science, and find Computational Materials Science experts.

Questions related to Computational Materials Science

I need the value of double partial differentiation of Gibbs energy (d^2G/dX^2)_eq at the equilibrium of a system. Does thermocalc/pandat calculate this term? If not, how can I get it from thermodynamic database?

Hello, I am interested in the simulation of island growth by the deposition of adatoms. As a beginner, which software is better to use; for example, the open-source MOOSE framework or COMSOL multiphysics? Thank you in advance.

I am searching for the CIF file of NiCo layered double hydroxide (NiCo-LDH). I have searched on the available online resources but could not get the file.

The CIF file for Ni

_{1}Co_{1}-LDH is high requested.Is there any way to convert the interaction energy among two systems into force?

I have two systems, wherein the 1st system destroys the configuration of 2nd system, owing to electrostatic interactions. What I suppose is that the 1st system is providing a certain amount of force that exceeds the total amount of energy required to hold the 2nd system in that specific configuration.

Hello everyone, I am currently working on a Heusler alloy system which has a

**non-collinear**magnetic order as reported by a earlier study. I intend to further explore this non-collinear magnetic state. It would be really helpful if someone can suggest me some properties that can be investigated**theoretically**in order to see if it has a potential use in spintronics devices or if it has some kind of other applications. I am using VASP. Thank you.How to calculate ΔG = ΔE + ΔEZPE - TΔS + ΔGpH + ΔGU, computational hydrogen electrode (CHE) model introduced by Norskov, the Gibbs free energy change (ΔG), using CASTEP code?

hello everyone, I am currently working on a Heusler alloy that has a very low spin polarization (below 10%). Can it still be used in spintronics devices? (usually higher spin polarization is preferred for spintronics application). Also, I should add that the antiferromagnetic state of the compound has almost twice the Magnetocrystalline Anisotropy Energy as compared to the ferromagnetic state (which is THE energetically stable state for the compound).

Hello,

I am investigating charge mobility and scattering rates using EPW software, but I am not sure how to do the convergence test. Is the decay sufficient or do I need to monitor the changes in mobility and scattering rates with changes in other input variables? ( which other properties can be used to confirm convergence?) Again, which input values/variables do I need to optimize?

Hello Everyone,

In many materials we can observe linear band crossing even above or below the fermi level. So what is the importance of having DIrac points somewhat away from fermi level (lets say around 2eV) ?

Can any crossing of bands which is linear leads to a DIrac point ?

Hello all, I am currently working on a system that contains Pt, and when I've plotted the 2D ELF pattern, this kind of plot was obtained. So, is there any kind of explanation for these kinds of plots?

Hello. Can anyone please tell me how to set INCAR/POSCAR for AF1, AF2 magnetic structure calculation, introducing different magnetic ordering for different planes? I tried making the POSCAR file using VESTA but I am not being able to turn off the symmetry completely. I thought if I turn off the symmetry I can set MAGMOM for each individual atom of a certain plane in the INCAR file but I am not being able to do so while creating the POSCAR file using VESTA. VESTA automatically fills up each corner position of the unit cell due to symmetry and therefore when I set MAGMOM in the INCAR file, one value of MAGMOM covers all the corner points, hence not being able to set different value/direction for different corner atoms

Hey,

Please share your work on UMAT and resources (except popular imechanica tutorial).

Thanks.

I have an idea to run some computational phase diagram codes on OpenCalphad , for a rather strange purpose

I have downloaded OC6 on windows 10, skimmed the user manual, browsed the GitHub page(https://github.com/sundmanbo/opencalphad), but nowhere found a simple code like finding equilibrium diagram for a binary alloy or ternary alloy at a given temperature. Googling is in vain, unfortunately.

Can any of you provide a simple step-by-step guide towards such simple to progressively complex problem?

I have found OC user manual to be not too user-friendly or pedagogically understandable to me.

I am facing an issue when calculating the dielectric function of Aluminum doped zinc oxide.

I am trying to replicate a paper and the imaginary part of the dielectric function is correct like in the paper I am trying to validate.

However , the real part of the dielectric function at the low energy region (0 to 0.5) should be negative, I am obtaining positive values, it seems that this part is reversed for some reason.

The rest of the real part data is correct.

I am using GGA- PBE- Norm conserving ultrasoft pseudo potentials.

I am really confused as I checked the documentation and it seems that the real part is calculated from the imaginary part, so how come I am getting these reversed values if the imaginary part is correct?

Thank you so much in advance.

Hello

Kindly refer the free energy functional for systems with elements A-B and A-B-C, in the attached image.

My question is, why the gradient of the dependent element (A) appears in multi-component system (2), while not considered in binary system (1)? It would be also better if you attach any references for derivation of (2).

Thank you!

I'm looking to simulate solidification following the Scheil model with back-diffusion in Pandat. I see, however, that a separate set of databases with .sdb format is required. Is this something that I have to get access to from somewhere or is it something that I need to create?

Hi, I've been an experimentalist throughout my career and I want to add to my knowledge and expertise in Materials Science by delving into computation, modeling and simulation. However, I'm very confused about where to begin as it appears that field of modeling and simulation is quite vast and expansive. If I had to choose a starting material type, I'd say composites and modeling of failure modes of composites. Can anyone guide me on where to begin? I'm a complete novice when it comes to anything computational. Where do I begin, if I'm starting from scratch.

I am currently doing my postdoc and planning to join some institute as a faculty by the end of this year.

My entire Ph.D. and postdoc durations were 95% experimental and 5% simulation. However, I am scared that if I join a new place as a faculty it will take so much time and resources to build an experimental lab from scratch. Hence, I am planning to learn some MD simulations (through a friend of mine who has a lot of experience) to kick start my research (in less time and resources) by the time the experimental lab is ready in the new university.

I need some suggestions from the experienced professors and postdocs in this thread about the possibilities, failure chances, risks involved, the correctness of Decisions.

The image is fed into MATLAB, The absolute value part of DFT of R,G,B pixels are separately determined, and the root-mean square value (RMS) of three DFT matrices (elementwise) are plotted into logarithmic contour plot (origin shifted to center) . The DFT contour plots have too much noise, but the version of MATLAB I use has no Gaussian filter available. The actual images are to the scale, and I want particle size distribution from the RMS-DFT.

I have already tried thresholding, but thresholding does not keep image of distinct grains distinct, and so the thresholded image is beyond recognition for grain size determination.

I have a cellulose model system that is best described by the GLYCAM06 force field according to the literature. However, the set of force fields included in the GROMACS package doesn't include the said force field. So, how do I include an additional force field in GROMACS? Or, can I even use other force fields not included in the package?

Without consulting the phase diagram (of still unexplored alloy systems) , how one can predict which alloying addition in an element would produce intermetallics with some given compositions? For example,

*how would one say that C is (one of the ) most crucial alloying element of Fe and Si of Al, with just consulting the periodic table and electronic structure*? Of course, there is no objective definition of "most useful" alloy- the same alloying element raising strength would not be the one that raises ductility.Some special properties can be reasoned as

- Strength and ductility- estimable by formulae for Solid solution, precipitation, dispersion and grain boundary strengthening- but
**how to physically link solid solution strengthening or Pierres-Nabarro stress of an alloy from electronic structures? Can ductility in these cases also be estimated from first principles?** - As for thermal and electrical properties, t
**he phonon/electron scattering data may be generalizable for a bigger group of alloys to find out thermal and electrical conductivities- but how**? The conductivity drop can be compared between solid solutions and intermetallic formers, but how to be sure that the alloy formed would be of any calculated phase distribution and of this certain electrical conductivity from first principles? - Corrosion resistance- The Pilling-Bedworth ratio is related to adherence of oxide or other protective films of metal- but
**how alloy composition can be related to strength, adherence and composition, and ultimately, reactivity of the protective film**? Relative position of EMF series can be, of course, estimated from total lattice energy, ionization energy and hydration energy.

I have just mentioned the two extremes of intermetallic formation and complete immiscibility- (complete miscibilities are well explained by hume-rothery rules, and ultimately also depends on how one objectively measures electronegativity), because there is, to my knowledge, no concrete rules to predict nature of phase diagram (isomorphous or eutectic or peritectic or monotectic or...) between two elements, let alone two compounds.

While electronic band structures of an element are available to be computed by standard methods, there is no systematic way to predict crystal structure or computed thermodynamic properties from composition alone (that are vastly generalizable).

I think there are scientific factors like cosmic and geological abundance, position in EMF series (and hence ease of extraction) as well as socioeconomic factors like market demand as choice for an alloying element. But is it possible to locate useful alloying elements for any of the elements with same unified rationale? (say of Mo, Ru, Rh, Pm, Tl)

And again, is there seemingly any way to tell which pair of metals or elements would be completely immiscible in solid states?

In theory, it is all about minimizing gibbs free energy, and from specific heat data of a solid, one can extract both values of enthalpy and entropy term. If this technique is generalizable for any solid, then why it is not used pervasively? is it because we just cannot predict the specific heat without crystal structure, and from chemistry alone, there is no way to predict crystal structure?

**Is it not possible to obtain Gibbs free energy of overlapping electron orbitals solely from schrodinger's equation, just like total energy is extracted from eigenvalues of Hamiltonian?**Hume-Rothery rules or Darken-Gurry maps are good starting points, but not good enough. Machine-learning based prediction can make things more systematic but without potentially answering the "why"s in a language familiar to humans .

**Interatomic potentials are scarce and very rarely generailizable**for any group of elements (like Lennard-Jones for gases). My question finally boils down to-**prediction of effect of alloying of any two elements, and ultimately composition to crystal structure and phase diagram calculation from first principle- is it even partially possible, if yes, how?****....................................................................................................................................**

*P.S: Honorable Researchers, Please provide related research papers related to these questions, along with your valuable feedbacks. I am unashamedly open to admit my severe incompleteness of knowledge, and I am far from being master of these field of science. SO feel free to point out where I have mistaken, and also*

**show me approach to synthesize such vast scientific knowledge into a coherent framework.**

*.............................................................................................................................................*See some of my related questions

- https://www.researchgate.net/post/What_can_be_theoretical_reason_for_these_patterns_of_Crystal_structures_in_periodic_table?_ec=topicPostOverviewAuthoredQuestions&_sg=qQHz-0jUZMihIai8gwUp1voPk-Tw5-YCl59uQgT88757TE3f6VQz9s6UGLULozUurbHcPQ3VJnXpw-YC
- https://www.researchgate.net/post/Is_there_any_special_rule_to_find_out_possible_room-temperature_stable_silicates_chemical_composition_if_not_crystal_structure_itself?_ec=topicPostOverviewAuthoredQuestions&_sg=qQHz-0jUZMihIai8gwUp1voPk-Tw5-YCl59uQgT88757TE3f6VQz9s6UGLULozUurbHcPQ3VJnXpw-YC
- https://www.researchgate.net/post/How-etchant-for-a-particular-alloy-system-is-developed-Can-it-be-estimated-from-first-principle-physics-chemistry-and-metallurgy?_ec=topicPostOverviewAuthoredQuestions&_sg=qQHz-0jUZMihIai8gwUp1voPk-Tw5-YCl59uQgT88757TE3f6VQz9s6UGLULozUurbHcPQ3VJnXpw-YC
- https://www.researchgate.net/post/What_are_the_factors_molecular_crystalline_structure_related_that_affect_refractive_index_of_ceramics_glasses_and_polymers_How?_ec=topicPostOverviewAuthoredQuestions&_sg=qQHz-0jUZMihIai8gwUp1voPk-Tw5-YCl59uQgT88757TE3f6VQz9s6UGLULozUurbHcPQ3VJnXpw-YC
- https://www.researchgate.net/post/How-computational-phase-diagram-techniques-can-find-Gibbs-free-energy-of-a-crystalline-phase?_ec=topicPostOverviewAuthoredQuestions&_sg=qQHz-0jUZMihIai8gwUp1voPk-Tw5-YCl59uQgT88757TE3f6VQz9s6UGLULozUurbHcPQ3VJnXpw-YC
- https://www.researchgate.net/post/How_can_symmetry_of_a_crystal_can_be_found_out_from_solely_electronic_structure_of_constituent_atoms?_ec=topicPostOverviewAuthoredQuestions&_sg=qQHz-0jUZMihIai8gwUp1voPk-Tw5-YCl59uQgT88757TE3f6VQz9s6UGLULozUurbHcPQ3VJnXpw-YC
- https://www.researchgate.net/post/How_binary_solution_models_were_derived_from_first-principle_thermodynamics?_ec=topicPostOverviewAuthoredQuestions&_sg=qQHz-0jUZMihIai8gwUp1voPk-Tw5-YCl59uQgT88757TE3f6VQz9s6UGLULozUurbHcPQ3VJnXpw-YC
- https://www.researchgate.net/post/How_crystal_structure_of_a_one-element_metallic_molecular_crystal_under_a_given_T_P_can_be_estimated?_ec=topicPostOverviewAuthoredQuestions&_sg=qQHz-0jUZMihIai8gwUp1voPk-Tw5-YCl59uQgT88757TE3f6VQz9s6UGLULozUurbHcPQ3VJnXpw-YC
- https://www.researchgate.net/post/What-decides-lowest-free-energy-crystal-structure-of-a-solid-at-a-given-temperature-and-pressure?_ec=topicPostOverviewAuthoredQuestions&_sg=qQHz-0jUZMihIai8gwUp1voPk-Tw5-YCl59uQgT88757TE3f6VQz9s6UGLULozUurbHcPQ3VJnXpw-YC
- https://www.researchgate.net/post/Why-metal-valency-affects-mutual-solubility?_ec=topicPostOverviewAuthoredQuestions&_sg=qQHz-0jUZMihIai8gwUp1voPk-Tw5-YCl59uQgT88757TE3f6VQz9s6UGLULozUurbHcPQ3VJnXpw-YC

Thank you very very much to hold your patience to read the whole post :)

I have created an Ice 1h crystalline structure and an Aluminium substrate structure and equilibrated both at 250K. Now I need to bring them together in a way that an adhesive bond is created. Reading the literature I have found that this can be achieved by an

**energy minimization process to bring the structure in contact and thereby inducing artificial stress at the interface**that can then be relaxed and a nucleation process can be started; but I don't grasp how this is done in LAMMPS.Any insight is appreciated.

As I was tweaking step-by-step OpenCalphad6 Macros step1.ocm involving phase and thermal property calculation of a High-speed steel, I could not incorporate more than 6 elements in the steel formula. Upon reading the OC6 Command-Line Interface, I came to know that, it was taking the element values from a database (SGTE SSOL2 database from 2001 for 6 elements) that contained only the six elements. How can I can any elemet in the steel as i wish during this kind of simulation?

Suppose one needs to find out room-temperature stable silicates chemical composition of a particular cation, suppose magnesium. Is there any rule to estimate which stoichiometric values of metal oxide: silica ratio would stabilize the binary silicate at room temperature? (i.e. in this example, how would I find out only Forsterite and Enstatite are of stable ratio, without empirically studying MgO-SiO2 phase diagram?)

At a first glance, the ratio seems to be consisting of any possible prime(and 1) numbers. Since its crystal structure is not known, Pauling's Rules also cannot be applied step-by-step to find out where silica tetrahedra are sharing corners, edges or faces.

Theoretical Computational and numerical simulation of phase diagram obviously can find out the stable ratios, but this is not what I ask for. I ask for tolerably simple chemistry rules like those provided by Hume-Rothery, Pauling or Goldschmidt, understandable with freshmen/sophomore chemistry/materials science/mineralogy knowledge.

I am currently using Quantum ESPRESSO to determine the minimum distance where the interaction between two nickel atoms becomes minimal. To do so, I set up a cube with two nickel atoms inside, one located at the origin and the other one along the body diagonal. For each calculation, the other nickel atom becomes farther from the one at the origin by an increment (0.5 angstrom).

Here is the sample quantum espresso input file:

&control

calculation = 'scf',

restart_mode='from_scratch',

prefix = 'ni_sep',

outdir = './outdir',

pseudo_dir = '<redacted>/GBRV',

verbosity='high',

/

&system

ibrav=1,

A=12.0,

nat=2, ntyp=1,

ecutwfc=90,

ecutrho=720,

occupations='smearing',

smearing='gaussian',

degauss=0.01,

nspin=2,

starting_magnetization(1)=0.3,

/

&electrons

electron_maxstep=300,

conv_thr=1D-9,

mixing_beta=0.7,

mixing_mode='TF',

/

ATOMIC_SPECIES

Ni 58.693 ni_pbe_v1.4.uspp.F.UPF

ATOMIC_POSITIONS {angstrom}

Ni 0.000000 0.000000 0.000000

Ni 3.464100 3.464100 3.464100

K_POINTS {automatic}

11 11 11 0 0 0

The problem is that the calculation runs more than 10 hours in my machine. I would like to ask for help in optimizing the input file. Thank you

Hi, I am trying to solve the motion of bubbles. The argen gas are injected from an inlet into liquid steel. Therefore the air generates the bubble. For the bubble motion I used DPM model and for the liquid steel, molten slag and top gas, I used VOF model.Now for the last step of my project I have to delete the bubble as soon as they impact the top gas. I wanna deleting bubbles with UDF.The idea for this UDF is that I want to delete the bubbles when they arrived at the position that the volume fraction of top gas is larger than 0.5. This is the UDF I am using:

#include "udf.h"

#include "dpm.h"

#include "sg_mphase.h"

DEFINE_DPM_SCALAR_UPDATE(stream_index,c,t,initialize,p)

{

cell_t c;

thread *t;

Thread *gas;

gas = THREAD_SUB_THREAD(t,2);

if(C_VOF(c,gas)>=0.5)

p->stream_index = -1;

}

Thanks.

I am good at DOS, Band structure and phonon studies. I would like to extend my studies to Dielectric and Ferroelectric studies. How to find the polarization in the material?

I am new to material simulation and I am willing to learn the theoretical aspects like what is k point mesh, how to interpret band diagram, how born charge results in IR spectra etc. I have experience of using DFT using gaussian 16 (modeling of reaction machnism) but don't have any experience in material simulation.

Thank you in advance.

In materials science, a

**dislocation**(line defect) represents a linear crystallographic defect within the crystal structure, which causes an abrupt change in the arrangement of atoms, which in turn influences several properties of materials. The**dislocation density**is a measure of the number of**dislocations**in a unit volume of a crystalline material usually having unit of lines per square meter (lines/m^{2}).Voids, pinholes, cracks, or inclusions like

**bulk defects**are the macroscopic regions, where there are no atoms and which can be thought of as clusters of vacancies. Usually, bulk defect density has the unit of per cubic centimeter (cm^{-3}).However, I would be highly obliged if any scholar provides me articles or mathematical equations (if any) to relate the dislocation density to the bulk defect density.

Thanks in advance.

I changed some of the Sn atoms' composition to 50%Sn and 50%Sb in the Co

_{2}TiSn 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?

Hi, i'm a physics student working in a project of materials science. I'm doing a simulation using LAMMPS.

In this case, i have a problem with the error Lost atoms: original 60536 current 56624 (../thermo.cpp:427) once i run the script. I'm trying to put a graphene sheet in a fix nvt 10 kelvin. But once the fix it's running, in 4 steps the velocity becomes irrational and I get the error.

Can you please guide me please? I'm new in all this.

Thank you for the help.

Dear Respected Members,

I did many tests to construct antiferromagnetic (AFM) ordering, which seems so hard to achieve. I build supercell of 2x2x1 containing 32 atoms of Mg16O16, and then replace two of Mg atoms by Cu atoms to get 12% Cu doped MgO (Mg14Cu2O16). My goal is to get the energy deference between the two configurations ΔE=EAFM−EFM from CASTEP code. Please check out the attached figures that I did and links to interpret the results using CASTEP code in materials studio. Please I need your experience and your valuable comments that will really put me on the right track. thanks.

the paper that I follow is "Ferromagnetism in Cu-doped MgO: Density-functional calculations"

DOI 10.1016/j.ssc.2014.06.002

Suppose, chemical composition of the compound, temperature and pressure are known. Electronic structure of constituent elements from numerical solution of Quantum chemistry are also known. Then

- There can be only about 230 3D crystallographic lattices. But is there any limit of motif that can be included into the lattice without violating stoichiometry? How ab-initio calculation find out the appropriate motif to put into lattice to generate crystal structure? Without finding motifs, it is impossible to find crystal structures whose Gibbs free energy needs to be minimized.
- Is there any mathematical method that finds out potential energy in an infinite 3D periodic lattice with distributed charges (say, theoretical calculation of Madelung constant)? What are the mathematical requirement/prerequisite to understand such formula?
- How electron cloud density and local potential energy of a molecule/ motif/lattice point can be linked to total Gibbs free energy of molecule/lattice integrated over the whole structure? What are the statistical-mechanical formula that relates the two? and what are the prerequisites to understand such formula?

Suppose reference point for zero gibbs free energy is conveniently provided.

I want to know; What are the tests and conditions that can be performed on a certain equation to say that it represents a good candidate for a multiscale model?

For a complex alloy (suppose Al-Si-Mg-Fe-Cu) , there are multiple linked potential files available in interatomic potential repository, but only a single potential file suffices for implementation of a single-element metal. Can you indicate me clearly how these declarations are done inside LAMMPS script file? Please provide with links to LAMMPS documentation.

I am a materials science undergrad, interested to know the algorithms for numerical integration of equation of motion in computational materials science, like molecular dynamics. It is said that, time-reversal symmetry is essential for such simulations, while classic integration schemes like Trapezoidal, simpsons or weddle methods handle previous and next time step differently. So verlet algorithm is used instead.

Position verlet indeed adds previous and past timesteps and maintains time-reversal symmetry. But velocity verlet doe not. Why is time-reversal symmetry not important for velocity? is it because time reversal symmetry is meaningful only for position and its even derivatives, as in newton's law of motion?

My knowledge on Numerical analysis is only of introductory level, and i have not deeply studied Lagrangian, chaos theory, group theory or hyper-dimensional geometry yet.

Octo-Alloy, also called Ashtadhatu, is a traditional alloy to produce religious idols, ornaments and sculptures in indian subcontinent. My question regarding the alloy is

- According to wikipedia,( https://en.wikipedia.org/wiki/ Ashtadhatu ), the alloy consists of gold, silver, copper, lead, zinc, tin, iron and antimony or mercury .
**Does this alloy consisting of so many dissimilar metals undergo phase separation during casting? Are there any research papers available about microstructure of this alloy, or about phase separation prevention of this alloy?** - Again, some ornaments, especially bangles made of this alloy are made in forms of two interwinning wires of different color. Which metals are incorporated into which wire?
**Where can I get credible Archeometallurgical and contemporary methods of casting (temperature, composition, time)and metalworking ( embossing, scribing) of this alloy?**Was this work of a jeweler, a sculptor or a metallurgist?**Is there any possibility that the alloy is a high-entropy alloy? Have there been any research on molecular dynamics simulation of high entropy alloy of these particular alloying elements?**I have not found any in interatomic potential repository**Had there been any research on***MEDICAL (NOT ASTROLOGICAL)*benefit of using octo-alloy( more specifically its self-disinfecting capability and heavy metal poisoning hazard)?

I need someone who has knowledge in SRIM-TRIM code for irradiation damage assessment to assess my designed code for me.

As a Materials scientist, how much necessary is to know about machine learning and Artificial intelligence in order to work on Computational Materials science? My own Computing skills do not go much beyond microsoft Office, and preliminaries of C, SolidWorks and MATLAB. So where to start? Please include references and links.

I want to make structure of DBT (C

_{12}H_{8}S) adsorbed TiO2 (100) surface. I have made TiO2 (100) surface from material studio, now I want to adsorb DBT molecule. How can make such type of structure in material studio ?Shilendra

If you are just interested in the energy of the system and this system has Fe atoms, will it matter to set the MAGMOM tag? Will it affect the computed energies or affect the convergence speed if set wrongly? Thanks.

I have a structure file. I want to input that structure file and get multiple structure files as output with varying lattice parameters. How can I do that using Atomsk. I want to vary the lattice parameter to be used in a LAMMPS simulation. Atomsk is capable of giving multiple output files with varying lattice parameter by bash scripting. But how can I do the same for complex structures?

As title, just roughly calculation is OK.thanks anyway

Please do not refer to JMatPro. It could not calculate for varying boron concentration in the given range.

Any paper describing the process would also be welcome.

Hi everyone!

I want to show band alignment of a hybrid halide perovskite material with an electron transport material ( Fig: CH

_{3}NH_{3}PBI_{3}and TiO_{2}, respectively). The position of VB edge (-5.4 eV/-7.3 eV) and CB edge (-3.9 eV/ -4.0 eV) can be known experimentally (XPS) in both materials (CH_{3}NH_{3}PBI_{3}/TiO_{2}). But can anyone tell me how can we calculate these values of the positions of VB/CB edges using VASP/WIEN2k?Thank you

I want to make Al/SiC structure in material studio. how can i do it? there is pure Al structure and SiC structure in material studio software. I want to delete group atoms from bulk of Al and replace them with SiC particles .

Dear respected RG members,

I am doing Mulliken population analysis of Cobalt (Co) doped MgO lattice (rocksalt) using CASTEP code (ultrasoft pseudopotential). I found some strange data as follow:

for

**pure MgO**bond population (Mg-O) =

**- 0.73**for

**(3%) Doped MgO**bond population (Mg-O) =

**- 0.31**bond population (Co-O) =

**0.42****Is the negative value of of Mg-O reliable?,**since negative value indicate antibonding, small value close to zero indicate ionic bonding and large positive value (Co-O) indicate covalent bonding. As we know, MgO has a very strong ionic bond, therefore bond population (Mg-O) must be close to zero. All parameters that I used during optimization are correct. I also did the same calculation using ( norm-conserving ). The obtained data gave almost a good result as suggest by Segall et al. (Mg-O = 0.58) and (Co-O = 0.53).

**Thanks in Advance**

Should I fix the k-point density and then increase the energy cutoff in steps until convergence, or should I fix the energy cutoff and then increase the k-point density in steps?

I am looking for some guidance on using forcite module for mechanical property. I'm creating crystal and when trying to do geometry optimization, selecting Compass, while assigning manually, getting some error. Am I missing something. Can you suggest some example manual for forcite module? Thanks.

I am a researcher of materials science and metallurgical engineering. I am interested to work with atomic level and electronic modeling of the structure and properties of materials,materials informatics and simulation in future. Currently i am learning

**. I have basics of***Python***and***C***. What will be the useful programming languages to learn for me?***MATLAB*Dear all,

I am trying to calculate ΔG of adsorbed species by using VASP. For this I need to calculate Zero point energies and Entropy of absorbed species. But I am confused with that. What type of calculations do I need to get ZPE and Entropy. Please help me in this case.

Thanks in advance.

anjibabu

Dear Experts,
I believe that there is no "arbitrary" things in science. Everything must be selected precisely with knowledge. I am trying to study the ferromagnetism in MgO rocksalt by introducing some defects Vmg and Vo using CASTEP code implemented in materials studio package. So, How can I select the position of vacancy in the supercell? Should I select all the position one by one and by comparing the formation enthalpy of each position and then choose the lowest formation enthalpy of that position. Your comments will really help me to understand more about this issue.
The figure bellow is 2x2x1 supercell of 32 atoms of Mg16O16 with two vacancy of Mg to give the formula Mg14O16. I got high magnetic moment based on Mulliken population analysis and oxygen high spin and low spin is responsible for this behavior.
Thanks in advance..
Mohammed

I want to use pp.x for calculation of work function for a semiconductor slab,

I have calculated the difference between the fermi energy and vacuum level using the plot_num=(1 and 11), for investigate the effect of including xc term.

Including xc term give rise to significant ( about 1 eV) decrease in total potential in vacuum region.

which one is physically meaningful?--considering xc potential or not?-

furthermore, the fermi energy in output is strongly sensitive to degauss value?

I think if we set occupation~fixed--without any smearing-- we should consider the VB edge as the Fermi energy at 0K.

I'm interested in learning to model ta-C and other (carbon) thin films deposited on solid substrates with PVD (FCVA). The modeled films could be up to 100 microns in thickness. Deposited film structure, intrinsic stresses, substrate bonding, electric properties, surfce topology and whynot protein adhesion would be some interesting characteristics to study with the model.

Also the eruption of ions and macromolecules by arc from the cathode could be an interesting modelling topic.

I thought to ask here if someone would have any recommandations on what software and modelling approach would be fruitful for this kind of research.

These alloys cannot deform via common deformation mechanism.

i am trying to use yambopy to my system. since i am a beginner at it, i can not really use it.

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

How can we calculate quantum capacitance as a functional of local electrode potential and stored charge on 2D materials by DFT calculations? Please post your answers including the procedure of calculation of capacitance properties of super-capacitor from DFT outputs by utilizing capacitance equations.

Thank you.

How to get values for the constants D

_{0}, E, α, β, T_{b}, K and effective plastic strain rate for flow stress model of Johnson and Cook in DEFORM software? Also brief that from where the values for other parameters i.e., A, B, C, m, n could be found?Hello everyone. I was hoping if anyone had information on material models for 3D printed parts. Specifically, it would be nice to have models for the plastics ABS and PLA. Thanks in advance.

- Do i compute it for a rectangular (parallelepiped) sample first and then make corrections for a cylindrical model?
- Can i use FEA or Finite Difference approach?
- Is it Ansys or Thermocalc which is best suitable?

Hi,

I found the total partial density of states but I would like find the each atom partial phonon density of states with PWScf package.

Thanks in advance.

Hello superiors,

I am looking for a method (which is compatible with VASP) to do Transport calculations on Surface Slab (say 111, 001 or 110 surface ).

I can do bulk transport calculation using BoltzTrap. BoltzTrap need space group for the calculation and I can easily provide space group for Bulk.

But when I am doing for an Surface what is the space group I need to give in BoltzTrap ??

My 2nd question is ----

how I can do Spin-Transport calculation on the surface of Topological Insulators ?

I will highly appreciate your anykind of comments.

Best Regards & Thanks,

Chanchal

While modeling amorphous materials computationally, I have seen papers using periodic boundary conditions. But glasses/amorphous materials doesn't have any periodic nature. Is it some kind of approximation? Or do we have some other way to model aperiodic materials?

How can we calculate the impurity (dopant) carrier (electrons and holes) concentration in the host material at 0K by DFT calculations and at room temperature by using semi-classical theory or some alternative method?

Is there anyway to calculate the impurity carrier concentration with BoltzTraP code?

I am vasp user.

I have the data concerning a simulated polycrystalline grain structure (the set of crystallographic directions). Each grain consists of minimum 1000 cells. I would like to obtain pole figures to analyze my data. How can I do it?

I have already tried to construct pole figures for untextured polycrystal using a stereographic projection. However, the results are weird, and, according to the pole figure (001) obtained, I do obtain the texture near the 001 pole.

I would be grateful if you could give me any advice or maybe suggest some literature.

Can anyone suggest a good simulation software for fiber reinforced polypropylene composites study? Open software with available tutorial is preferred. Thanks!

Interested researcher may wish to send their email as well to future communications. We’ve some experimental results already & need DFT calculations to have a deeper insight into the system.

**Please only reply in case you are really interested and have some time to devote for our problem.**We aim to finish this work soon & publish under this joint collaboration.Figure 1 (from Langmuir, 2013, 29 (7), pp 2175–2184) shows a typical sequence of approaching, colliding, and departing of a pair of nanospheres in a MD simulation. Initially, the two nanospheres move close to each other (Figure 1a) at an initial relative velocity of Vr,0 =300 m/s. Then, they continue moving toward each other and reach a position of close proximity (Figure 1b). After that, the overlapping of two nanospheres occurs (Figure 1c). Figures 1d, e, f demonstrate the following dynamic departing process. It is shown that the two nanoparticles can rebound out of the reach of each other after the overlap if a very large initial velocity is applied. Changing the initial relative velocity Vr,0 will produce different collision dynamics. I am trying to repeat this in Materials Studio 2016 for my research. Please help.

Efficient DFT code for large quantum dots?