How to calculate the elastic properties of MgO using Elastic code

 

 

Elastic is a code developped by Paweł T. Jochym

Elastic is a set of python routines for calculation of elastic properties of crystals (elastic constants, equation of state,sound velocities, etc.)

 For more information check the manual

 

 To install the code click on the following link:

https://vasp-algerien1970.blogspot.com/2022/08/how-to-download-and-install-elastool_4.html

To execute the code we take the example of MgO

We the following input files

POSCAR

Mg  O 
 1.0000000000000000
     4.2004725253589212    0.0000000000000000    0.0000000000000000
     0.0000000000000000    4.2004725253589212    0.0000000000000000
     0.0000000000000000    0.0000000000000000    4.2004725253589212
  Mg   O
   4   4
Direct
  0.0000000000000000  0.0000000000000000  0.0000000000000000
  0.0000000000000000  0.5000000000000000  0.5000000000000000
  0.5000000000000000  0.0000000000000000  0.5000000000000000
  0.5000000000000000  0.5000000000000000  0.0000000000000000
  0.5000000000000000  0.5000000000000000  0.5000000000000000
  0.5000000000000000  0.0000000000000000  0.0000000000000000
  0.0000000000000000  0.5000000000000000  0.0000000000000000
  0.0000000000000000  0.0000000000000000  0.5000000000000000

 

INCAR

INCAR created by Atomic Simulation Environment
 EDIFF = 1.00e-08
 GGA = PE
 PREC = Accurate
 IBRION = 2
 ISIF = 2
 NSW = 30
 LREAL = A
 LCHARG = .FALSE.
 LWAVE  = .FALSE.
 ALGO = Fast
 NPAR = 4

 

KPOINTS

KPOINTS created by Atomic Simulation Environment
0
Monkhorst-Pack
3 3 3 
0 0 0

 

POTCAR

You can get the POTCAR file from the following link:

https://github.com/jochym/Elastic/blob/master/tests/data/POTCAR

or clone the hole directory

git clone https://github.com/jochym/Elastic.git

The script  cal.sh (wich is a modification of the original script)

#!/bin/bash
# Command to run vasp in current directory
RUN_VASP="vasp_std"

N=$(ls cij_* | wc -l)
M=$(($N-1))

for s in $(eval echo "{000..$M}")

do
    d=${s%%.POSCAR}
    mkdir calc-cij_$d

(
     cd calc-cij_$d
     cp  ../INCAR  INCAR
     cp  ../POTCAR POTCAR
     cp  ../KPOINTS KPOINTS
     cp ../cij_$d.POSCAR POSCAR
     
$RUN_VASP

     cd ..
)

done

Calculation

algerien1970@........./MgO-elastic> chmod +x cal.sh 

algerien1970@........./MgO-elastic> conda activate elastic

(elastic) algerien1970@......ls/MgO-elastic> elastic -v --cij gen -n 5 -s 2 POSCAR

(elastic) algerien1970@......ls/MgO-elastic> ./cal.sh

(elastic)../MgO-elastic> elastic -v --cij proc calc-cij_000/vasprun.xml calc-cij_*/vasprun.xml
Reading: calc-10/vasprun.xml                                         
Cij solution
------------------------------
 Solution rank:  3
 Square of residuals: 0.00049
 Relative singular values:
 1.0000   0.7071   0.6354  

Elastic tensor (GPa):
   C_11     C_12     C_44  
------------------------------
 321.52    96.27   143.42