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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8 votes
1 answer
256 views

Comparing results of various DFT calculations in Quantum ESPRESSO

To verify the reliability of calculation scheme, I want to compare lattice constants, bond length and band gap calculated by the different functionals with the experimental results. So in order to do ...
2 votes
0 answers
21 views

What considerations should be kept in mind to ensure accurate matching of elastic constants in VASP calculations?

What factors should be considered to ensure accurate alignment of elastic constants obtained from VASP calculations with those reported in the literature for 2D hexagonal graphene?
1 vote
1 answer
66 views

How to compute the Elastic Modulus of a molecule using GROMACS?

Say we take the basic example of a PEG molecule (PolyEthylene Glycol). What is the fundamental physics for computing the Elastic Modulus or the Young's Modulus from the Molecular Dynamics (MD) ...
3 votes
1 answer
159 views

Dielectric tensor εij (total)

How may I calculate the Dielectric Tensor εij (total) like here? In the OUTCAR, I see both ...
6 votes
0 answers
81 views

Predicting the band gap or some other properties of materials before running any calculations [closed]

Can we somehow predict what sort of modulation doping will do to a material without actually running any calculations? For instance, could we use the already known density of states (DOS) of Zn to ...
11 votes
1 answer
422 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 ...
1 vote
1 answer
52 views

Number of electrons per cell

I aim to do a HF-like calculation on a 2D graphene layer. What is the number of electrons per cell? Edit: There are six carbon atoms per cell.
3 votes
0 answers
58 views

Are then any material property solvers (from Charge Density) available in python?

I am looking to predict properties like the Bulk Modulus, total energy, etc., all from the charge density I have as input (CHGCAR file)
2 votes
1 answer
65 views

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,...
5 votes
0 answers
78 views

Reference textbooks for calculating pressures/stress/strain/tensors? [closed]

Is there a good reference textbook for calculating pressures/stress/strain/tensors in materials - vapor, liquids and solids? Pure physics is fine, but it would be a bonus if it also included force-...
9 votes
0 answers
106 views

How to go from zero to hero in Machine Learning for materials modelling

I am interested in exploring the use of machine learning tools to accelerate molecular dynamics simulation probably by training machine learning potentials. While I have found some papers that apply ...
5 votes
1 answer
35 views

Database on calculated molecular vibrations including coordination complexes?

Related to the question Are there dashboards displaying experimental properties of molecular materials? My question is: Are there any good, free, online databases on calculated vibrational modes of ...
3 votes
0 answers
70 views

Calculating bulk modulus of aluminum using pymatgen and MLIP

I have an interatomic potential (CHGNet) which is interfaced with pymatgen and can output the stress on any structure. Now, I want to use pymatgen to calculate the bulk modulus for aluminum. The code ...
4 votes
0 answers
64 views

Explicit calculation of Poisson's ratio using energies from a potential energy surface [closed]

I would like to calculate the above quantities for a given unit cell (or supercell) with arbitrary symmetry. Specifically, I am trying to use a machine-learned interatomic potential (MLIP), and since ...
6 votes
1 answer
107 views

How can I calculate the elastic properties of a unit cell and a supercell?

Can someone please share with me a method to compute the elastic constants of the unit cell and doped supercell of a material? In my calculation I use Quantum ESPRESSO. And I already tried Thermo_pw, ...
2 votes
0 answers
64 views

Query about NiO structure

I have one query about the NiO structure. As per the literature, NiO is a rocksalt type of structure ( NaCl type) and exhibits an antiferromagnetic ordering of type-II cubic (fcc). I considered the ...
5 votes
1 answer
148 views

Calculating theoretical density from .cif files

I'm studying structure-property relations in MOFs and have a pool of hypothetical structures in .cif format generated using ToBaCCo code. I want to filter them based on theoretical density, but the &...
1 vote
0 answers
12 views

why can a defect have a lower barrier strength compared with another defect but still have a larger effect on embrittlement? [closed]

I have read that for a particular alloy system, a specific precipitate has a low barrier strength to plastic deformation in comparison to dislocation loops. However this precipitate gives the largest ...
2 votes
0 answers
62 views

How to Find the Huang-Rhys factor from the Intensity Vs Wavelength plot (PL plot)?

How can I find the HR factor like we calculate the Debye waller factor as - log(IZpl/Itotal), from the intensity profile of the PL spectra.
3 votes
1 answer
489 views

Noob Question: How can I write bulk, monolayer and bilayer structure in input file for visualizing it

I'm getting my bachelor degree in physics and in my structure of matter course we never talked about bulk, monolayer and so on. I can understand Bravais lattice , reciprocal lattice and so on but I'm ...
2 votes
1 answer
142 views

Is there any effect on the physical properties when the size of the system increases in DFT?

I am using Quantum ESPRESSO to do some DFT calculations. I want to know if the optoelectronic properties obtained by a unit cell would remain the same when the properties are obtained by using a ...
4 votes
1 answer
250 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 ...
3 votes
1 answer
52 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 ...
3 votes
0 answers
34 views

What determines if a material tends to undergo transgranular or intergranular fracure? [closed]

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 ...
4 votes
2 answers
654 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....
5 votes
1 answer
338 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 ...
4 votes
0 answers
73 views

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

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: ...
3 votes
0 answers
25 views

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

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 ...
3 votes
1 answer
123 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 (...
9 votes
2 answers
1k 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.
20 votes
3 answers
331 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 ...
5 votes
1 answer
112 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 ...
3 votes
1 answer
65 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}{...
3 votes
0 answers
104 views

Calculation of quantum capacitance for materials using Quantum Espresso [closed]

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 ...
6 votes
1 answer
325 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, ...
3 votes
0 answers
101 views

Is there a way to estimate the energy of desorption of an adsorbed molecule? [closed]

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 ...
6 votes
2 answers
216 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 ...
6 votes
3 answers
3k 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&...
5 votes
1 answer
2k views

Elastic constants calculation

I am doing elastic calculations using VASP code in which OUTCAR contains four different elastic moduli: ELASTIC MODULI , ...
5 votes
1 answer
390 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 ...
3 votes
1 answer
39 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 ...
2 votes
0 answers
102 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,...
4 votes
1 answer
276 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 ...
6 votes
0 answers
123 views

Analytical derivative method in ab initio molecular properties calculations [closed]

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&...
4 votes
0 answers
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 ...
6 votes
1 answer
568 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 ' <...
6 votes
1 answer
312 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 ...
3 votes
0 answers
111 views

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?
9 votes
1 answer
226 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),...
8 votes
1 answer
788 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 ...