# Questions tagged [elasticity]

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### 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 ...
184 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 ...
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 ...
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?
23 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?
459 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 ...
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
105 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) ...
338 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 ...
84 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 ...
67 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 ...
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 ...
131 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, ...
161 views

### How can I calculate the in-plane stiffness and Poissonās ratio of a graphene monolayer?

I used a 2x2x1 rectangular supercell of graphene to calculate the elastic properties (in-plane stiffness and Poissonās ratio). The in-plane stiffness can be given by the following equation, C^2D= \...
212 views

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 ...
341 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 ...
275 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 ...
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 (...
134 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%...
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 ...
801 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, ...