Questions tagged [elasticity]
Questions about elasticity of materials.
28
questions
14
votes
1
answer
1k
views
Is LDA better than GGA for elastic constants?
I have calculated elastic constants for Si, GaAs, and GaN using LDA and GGA in VASP.
LDA is giving better results than GGA for elastic constants.
Is there is a reason behind the good results by ...
- 706
11
votes
1
answer
174
views
How can we make a mechanically unstable cubic system, stable
I have to calculate the elastic constants of a Cubic system using a Density functional theory-based software. A cubic system will be mechanically stable if it satisfies the Born-stability condition (...
- 1,663
10
votes
2
answers
480
views
Temperature effect on elastic constant using VASP
I want to incorporate the temperature effect on elastic constant (EC) of a system using VASP.
From literature, there are two ways which can be used to get the temperature effect on EC i) ab initio ...
- 866
9
votes
2
answers
493
views
Problem related to the calculation of elastic constant with VASP5.4.4
I am using VASP5.4.4 to calculate the mechanical properties of the cubic phase SnTe. The structure can be found in the materials project website.
In detail, I use the following INCAR to calculate the ...
- 14.9k
9
votes
1
answer
3k
views
How to use the ev.x tool in Quantum ESPRESSO?
The requirement I have is to calculate the bulk modulus from the energy values at certain volumes obtained via DFT calculations. Can you provide the instructions to use the ev.x tool in the Quantum ...
- 4,448
9
votes
1
answer
738
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, ...
- 191
7
votes
1
answer
148
views
How to calculate 2D elastic constants of boron nitride monolayers from uniaxial strains?
I am trying to calculate 2D elastic constants of a hexagonal boron nitride (hBN) monolayer.
The unit cell is the primitive cell and the Cartesian coordinate is set as follows.
The elastic constants $...
- 400
6
votes
2
answers
154
views
Fitting of Brich-Murnaghan equation of state
After performing high-pressure calculations for my ABO4 compounds using the VASP software, I am now interested in fitting the Birch-Murnaghan equation of state to either pressure versus volume or ...
6
votes
1
answer
70
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, ...
- 1,957
6
votes
1
answer
263
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 ...
- 5,683
6
votes
0
answers
126
views
How to optimize the geometry of beta PHB in VASP? [closed]
I would like to calculate the elastic constants of beta PHB. From this paper. I know that it has P3221 space group. The beta PHB has upward and downward chains, which exist at one lattice site with 50%...
- 191
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 , ...
- 529
5
votes
1
answer
190
views
elastic constants transformation/basis change P21/a -> P21/n
I just calculated the stiffness tensor for a given material (a monoclinic molecular crystal)
using molecular simulation. When trying to compare my results to published experimental results
I found ...
5
votes
1
answer
101
views
How can I calculate the in-plane stiffness and Poisson’s ratio of a graphene monolayer?
I used a 2x2x1 rectangular supercell of graphene to calculate the elastic properties (in-plane stiffness and Poisson’s ratio). The in-plane stiffness can be given by the following equation,
$$C^2D= \...
- 195
4
votes
1
answer
236
views
How to do a proper relaxation of the multicomponent structure?
I have a beta Ti (Space Group 229) structure with 16 atoms, I prepared 15 disordered TiNb structures with 5 atoms of Nb. I did it using VASPKIT. However, before the ...
- 191
4
votes
1
answer
435
views
Elastic constant calculation
I want to calculate elastic constants with VASP "by hand" (not by, e.g., DFPT) as I have a big structure (64 atoms). For this, I am making tests on $\ce{Si}$ at the moment.
So, I have done ...
- 91
4
votes
0
answers
58
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 ...
- 71
3
votes
1
answer
396
views
How to start with the elastic properties of 2D materials using the VASP code?
I have some experience in dealing with structural, electronic, and magnetic properties of 2D materials, but I want to go further to study the elastic properties. Could you please guide me on this? ...
- 5,683
3
votes
1
answer
223
views
Elastic properties of graphene by using DFT (Quantum espresso)
I am a Ph.D. student. I am using Quantum Espresso to calculate the mechanical properties ( in-plane stiffness ) (undergo uniaxial strain). I calculated the strain energy of each applied strain. The ...
- 195
3
votes
0
answers
46
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 ...
- 71
3
votes
0
answers
36
views
What is convention of predefined coordination system for defining elastic constant of a specific material
I try to find the elastic constants of LiTaO3 from online databases. I did find a page that lists them https://www.roditi.com/SingleCrystal/Lithium-Tantalate/LiTaO3-Properties.html
As I know, the ...
- 223
2
votes
0
answers
21
views
how can I calculate Poisson's ratio of graphene monolayer (2D material)
How can I calculate the Poisson's ratio of graphene monolayer, where I got the in-plane stiffness along the x-axis? most of the papers use this equation
ES = b1Ꜫx2 + b2Ꜫy2 + b3ꜪxꜪy
to calculate the ...
- 195
2
votes
0
answers
28
views
Is it a good idea to always read charge and orbitals if I am working on similar systems?
For example, if I am investigating of the elastic properties of a crystal by doing a lot of computations of crystals applied with small strain.
Also, is it a good idea to read charge and orbitals when ...
- 401
2
votes
0
answers
89
views
Calculating strain field. Need idea on how to do that
Recently I am learning VASP. I am trying to see different properties of two-level system (TLS). For example, checking amorphous silicon as a test case (along with it's vacancy structures as well). ...
- 859
2
votes
0
answers
100
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,...
- 529
1
vote
0
answers
33
views
why should we use rectangular supercell of graphene instead of hexagonal supercell to calculate the elastic constant (in-plane stiffness) [closed]
Most researchers use rectangular supercells instead of hexagonal supercells of graphene to calculate the mechanical properties. All of the articles are working on mechanical properties, they ...
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