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Questions tagged [elasticity]

Questions about elasticity of materials.

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2 votes
0 answers
38 views

Stiffness constants C11

How can I accurately extract and reproduce the values of $C_{11}$ for 2D hexagonal structures with two independent in-plane constants $C_{11}$ and $C_{12}$? I've used Vaspkit to extract a value of ...
6 votes
1 answer
183 views

Elastic property in Voigt, Reuss and Hill approximations

DFT tools e.g. vaspkit after post-processing elastic calculation results provide elastic properties, say, bulk modulus for bulk single crystal and bulk polycrystal. Bulk single crystal values are ...
5 votes
1 answer
176 views

What is a good material to use in a blood vessel model? [closed]

I'm trying to create a training model for neurosurgery that utilizes 3D printed bones and associated vessels. I intend to use a pump to run artifical blood through these vessels. So they need to be ...
3 votes
1 answer
48 views

Assessing Accuracy of Elastic Constants for 2D Materials Calculated via VASP and VASPKIT

How can one assess the accuracy of elastic constants for 2D materials calculated via VASP and VASPKIT in the absence of literature guidance?
2 votes
0 answers
22 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?
8 votes
1 answer
427 views

Exploring Elastic Constants Calculation in VASP: Methods and Best Practices

I'm interested in calculating elastic constants for 2D (monolayer) using VASP and I'm looking for guidance on the necessary steps. Could anyone here provide some insight into how to go about this ...
4 votes
1 answer
72 views

Supercell Elastic Constant

Suppose, that one wants to study a bulk structure which is doped by several impurities. More precisely, I want to calculate the elastic constants using a DFT code (VASP) by fitting stress to strain (...
1 vote
1 answer
104 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) ...
6 votes
2 answers
329 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 ...
3 votes
0 answers
83 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
66 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 ...
3 votes
0 answers
37 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 ...
6 votes
1 answer
128 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, ...
5 votes
1 answer
160 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= \...
7 votes
1 answer
210 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 $...
2 votes
0 answers
35 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 ...
3 votes
1 answer
453 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 ...
1 vote
0 answers
41 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 ...
2 votes
0 answers
30 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 ...
2 votes
0 answers
109 views

Calculating strain field. Need idea on how to do that [closed]

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). ...
3 votes
1 answer
555 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 votes
1 answer
3k views

Elastic constants calculation

I am doing elastic calculations using VASP code in which OUTCAR contains four different elastic moduli: ELASTIC MODULI , ...
2 votes
0 answers
105 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,...
10 votes
2 answers
577 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 ...
4 votes
1 answer
583 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 ...
14 votes
1 answer
2k 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 ...
6 votes
1 answer
337 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 ...
4 votes
1 answer
274 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 ...
11 votes
1 answer
182 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 (...
6 votes
0 answers
133 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%...
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 ...
9 votes
1 answer
800 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, ...
5 votes
1 answer
234 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 ...
9 votes
2 answers
574 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 ...