# Questions tagged [physical-properties-of-materials]

Questions about modeling or theoretical/computational values for physical properties of materials such as ductility, Young's modulus, malleability, conductivity, specific heat capacity, density, etc.

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189 views

### What is the best method to compute crystal structures?

I am rather new to VASP and I have seen people using different methods to compute crystal structure: Using Birch-Murnaghan equation to find optimal lattice volume, and then adjust the structure ...
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22 views

### Why is strain rate used instead of absolute strain for modelling stress relaxation of a viscoelastic material using the Maxwell model?

I don't quite fully understand the derivation of the Maxwell model for prediction of stress relaxation for viscoelstic materials. usually the governing equation can be described in terms of strain ...
22 views

### What determines if a material tends to undergo transgranular or intergranular fracure?

As an example, why does glass tend to break by means of intergranular fracture? My analysis so far led me to believe that the tendency can be related to the intermolecular bond strength in a given ...
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299 views

### What's the meaning of k-points with weight zero?

In a post from the Quantum Espresso mailing list, a user suggests adding k-points with weight zero to an SCF calculation as a workaround to allow bandstructure to be computed using a hybrid functional....
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170 views

### How to calculate lattice parameter?

After 'vc-relax' calculation I got the cell parameters in the picture bellow. I want to mention that my ibrav=1. I think the optimized lattice parameter in this case is A=11.44879234*1.006676454 .But ...
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38 views

### How to implement Ueff​=U−J in a Quantum ESPRESSO input file?

I want to implement Ueff​=U−J in a Quantum ESPRESSO input file, but I don't know how to do that. I found the following on the internet: ...
• 1,439
19 views

### Do I have to repeat my previous calculations after increasing 'diago_david_ndir' in the input file of the bandstructure calculations?

After doing the convergence test, 'vc-relax' and 'scf' calculations for my material using Quantum ESPRESSO everything went well. But when I wanted to do a 'bands' calculation for bandstructure I got ...
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1 vote
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### Are the cell parameters found after doing a 'vc-relax' calculation the ones used to calculate the material properties?

I created a CIF file using the experimental data from literature . After doing a 'vc-relax' calculation do I have to change the lattice parameter, CELL_PARAMETERS and ATOMIC_POSITIONS in my input file,...
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67 views

### How to Model Antiferromagnetic NiO p-type semiconductor?

I'm a beginner in DFT and I want to study the properties of NiO and doped-NiO materials using Quantum ESPRESSO.I found in the internet that I should introduce the spin magnetization in the Input file (...
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48 views

### What software can simulate bulk magnetism?

I am interested in investigating bulk magnetism computationally. What are the packages available for it? Any help in this direction will be appreciated. Please answer with the format of the answer in ...
360 views

### Software recommendations to construct band structures using tight binding

I am at the beginning of computational materials modeling. My objective is to calculate the electrical conductivity of a system that consists of several thousand atoms, and running DFT calculations is ...
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48 views

### Bending rigidity of the nanomaterial from MD simulation

The literature seems to be very diverse in measuring the bending rigidity of the nanomaterial from MD simulation. I have seen people often use this relation from continuum mechanics k = \frac{Eh^3}{...
66 views

### Calculation of quantum capacitance for materials using Quantum Espresso

I wish to run DFT calculations on Quantum Espresso for the calculation of quantum capacitance. I have gone through literature, specifically, "Graphitic carbon nitride decorated with FeNi3 ...
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212 views

### Software for Molecular Dynamics in Material Science

I would like to know available software that can do Molecular Dynamics (MD) simulations for any type of system, specifically inorganic and organic ones. The must cited MD packages (GROMACS, AMBER, ...
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47 views

### Is there a way to estimate the energy of desorption of an adsorbed molecule?

I'm studying the adsorption of several molecules in metal organic frameworks (MOFs) using both experimental and computational methods. Experimetally I can easily obtain the temperature at which a ...
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2k views

### Difference between "electrical" and "electronic"?

I found that people often measure "electrical conductivity", but some may say "electronic conductivity". Can anyone explain the terms "electrical" and "electronic&...
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762 views

### Elastic constants calculation

I am doing elastic calculations using VASP code in which OUTCAR contains four different elastic moduli: ELASTIC MODULI , ...
• 519
37 views

### Spacing issues about multiple-layer bcc structure

I am trying to make Hartree potential of bcc Tungsten(001). My software is VASP. 5-layer should have 5 bound states. But I don't have them I heard it is a layer-layer spacing issue. I built slab of ...
85 views

### study of elastic properties under pressure using VASP [closed]

I want to replicate this paper, but somehow I cannot get the same results, most important as shown in table 2. Can anyone help me with this? I have attached the INCAR file. If any correction is needed,...
• 519
156 views

### How to map high symmetry points from primitive cell to conventional cell?

We usually plot electronic bands with the help of high symmetry points of the irreducible zone of primitive cell of particular material. But if we want to plot bands with conventional cell, we have to ...
• 113
96 views

### Analytical derivative method in ab initio molecular properties calculations

In order to relate results from quantum chemical calculations to experiment, it is essential to compute quantities that are directly available from measurements. Properties describe the "response&...
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36 views

### Predicting the band gap or some other properties of materials before running any calculations

Can we some how predict what sort of modulation will doping do to a material without actually running any calculations. Like perhaps we use the already known DOS of Zn in order to predict whether the ...
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235 views

### How to estimate chemical potential at a temperature?

Fermi level is electron chemical potential at 0K and we can obtain it from DFT calculation. However, the chemical potential is dependent on temperature. But I only find the equation for gas or simple ...
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53 views

### Recommendation for some papers on simulation of metallic metal

I want to simulate the collision between two gas giants, the inner layer of gas giant contains the layer of metallic hydrogen and a solid core, if two gas giants collide then the abrubt variation of ...
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88 views

### Examples of anti-symmetric rank-3/4 tensors?

The anti-symmetric rank-3 and rank-4 tensors hold the following properties: \begin{align} \sigma_{mnk} &=-\sigma_{nmk} \\ \sigma_{mnkp} &=-\sigma_{nmkp} \end{align} Note I'm using ...
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327 views

### Cohesive energy of Cu with Quantum Espresso

Using this input Cu FCC vc-relax method error to calculate Ebulk, I'm trying to calculate the cohesive energy of solid Cu (Ecoh = Eatom − Ebulk). For the Eatom I'm using a similar input but with ' <...
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168 views

### What is the difference between elastic and mechanical properties of materials?

I have seen many articles[1] that write in the title "mechanical properties of ...", but in the subsections of the paper, they write "elastic properties" and discuss elastic ...
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### Why is there a deviation between the experimentally calculated values and theoretical done by DFT calculation? [duplicate]

If there was a deviation between the experimentally calculated values and theoretical determination done by DFT calculation, then what is the reason?
157 views

### Are there tools to calculate the electrical conductivity of large (>1000 atom) nanostructures?

Are there any free to use tools which can be used to calculate the electrical conductivity of nanostructured materials. The systems that I am interested in consist of several thousand atoms, and ...
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176 views

### How to find the Cauchy stress tensor in solids using ab-initio methods?

I want to find the Cauchy stress tensor in certain materials with ab initio methods. I already have the analytical form of my own definition of "energy" and "forces" (not from DFT),...
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132 views

### About LaCrO3 space group stability

I found two space groups of $\ce{LaCrO3}$ material Pnma and Pm-3m. If someone is familiar with this material, please help to understand which phase is more stable. what are the factors that determine ...
48 views

### Compute bulk electrical conducitivity from single-crystal measurements [closed]

If I have single-crystal measurements of electrical conductivity along 3D axes (considering for example anisotropic materials), is there any straightforward way to compute the bulk (global) electrical ...
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87 views

### Why do some decanters dry quickly, and others dry slowly?

My decanters are washed in hot water. The outside is then dried with a clean cloth, as is the top of the inside of the neck — typically one can’t reach further. The still-warm decanter is then left ...
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515 views

### Viscosity calculation using molecular dynamics simulations

I use the GROMACS software for MD simulations and I am trying to understand the calculation of viscosity using combinations of different ensembles and different methods. For a non-equilibrium MD ...
• 1,347
33 views

### Linear combination of homogenized composite material [closed]

My research is on the structural optimization of fibre-reinforced composite material (transversely isotropic material). I am currently working on a homogenization method for attaining the effective ...
524 views

### Calculating lattice thermal conductivity using Quantum ESPRESSO and phonopy

How should I calculate lattice thermal conductivity in Quantum ESPRESSO? I have installed phonopy. My Linux distribution is Ubuntu.
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106 views

### Large dataset with conductivities of materials and chemical compounds? [closed]

I'm looking for a fairly large (>100k) dataset of chemical compounds (and materials) that has conductivities. I've looked at PubMed, but couldn't find conductivities. I would ideally like to avoid ...
96 views

### How to calculate the thickness of the slab when simulating a bulk surface? [closed]

The method I found, which seems to be the most commonly used for simulating surfaces, involves constructing a slab and doing a structural optimization by freezing a few of its lowermost layers. What ...
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272 views

### Mathematical models for the plastic region in the tensile test

The tensile test of a material consists of subjecting a standardized specimen to an increasing axial tensile stress until it breaks. During its performance in the laboratory, we can plot a stress-...
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138 views

### Is "Valence Electron Density" and "Electron Density" data of a molecule the same thing? [closed]

I'm wondering specifically in the context of calculating physical properties from valence-electron-density data using DFT, MD, and or ML (machine learning).
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316 views

### Are there dashboards displaying experimental properties of molecular materials?

A dataset is generally a collection of data. A database is an organized collection of data, allowing different kinds of queries. A dashboard is a graphical user interface that is employed to make ...
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649 views

### Why VASP calculates the elastic constant for another trigonal space group?

Please, help me to understand the problem. I calculated the elastic constants for the beta PHB (Space group P3221 (154)), it has to show the reduced elastic constant matrix (six), however, ...
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300 views

### How to calculate the volumetric energy density of a molecule?

I am trying to store hydrogen in a hydrocarbon. The example can be taken as cyclohexane ($\ce{C6H12}$) which is in a hydrogen-rich state. Its hydrogen-lean state is Benzene. I want to calculate the ...
• 1,663
142 views

### Has it been researched whether face centered cubic carbon is stable?

According to this paper, carbon has a face centered cubic phase which is a metallic form. My question is: Has it been researched whether face centered cubic carbon is stable? Reasons why I'm ...
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### Has there been research on improving the strength of graphene-based materials?

I read that brittle materials tend to have an observed strength much less than its theoretical strength because they tend to have surface cracks and whatever tension is applied gets greatly magnified ...
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68 views

### Value of density of state effective mass and transport effective mass to calculate conductivity [closed]

How can density of state effective mass and transport effective mass can be defined to calculate conductivity for a cubic system with parabolic but anisotropic dispersion relation? What will be the ...
• 1,575
165 views

### How to study a new material without any experimental data about it?

My question is a little bit general. I want to study a 2D monolayer material which hasn't any experimental data available, just some first principles DFT works using PBE, LDA and HSE06 (for band ...
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1k views

### Selection of appropriate Langevin damping parameter for MD of solid metal

I am performing an MD simulation involving solid metal. The system is in the NVT ensemble, and I am using the Langevin thermostat (fix Langevin in LAMMPS) to enforce this. I have previously used the ...
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