Basic calculations using VASP

Lattice optimization

This part includes the optimization of lattice parameters and ionic position.

Lattice parameters

For cubic, we can use the ISIF=2 + change the scale factor in POSCAR, using the Birch-Murnaghan Equation to obtain the optimized values.

Birch-Murnaghan equation of state:
$$
E(V)=E_{0}+\frac{9V_{0}B_{0}}{16} \left{ \left[ \left( \frac{V_{0}}{V} \right)^{\frac{2}{3}} -1 \right]^{3} B_{0}^{‘} + \left[ \left( \frac{V_{0}}{V} \right)^{\frac{2}{3}} -1 \right]^{2} \left[ 6 - 4 \left( \frac{V_{0}}{V} \right)^{\frac{2}{3}} \right] \right}
$$

For example:

We have INCAR, KPOINTS, POTCAR, vasp.sh in fold ./origin.

We can use the rs.sh:

#!/bin/sh
for i in $(seq 0.970 0.005 1.030)
do
mkdir bm$i
cd bm$i
cp ../origin/{vasp.sh,POTCAR,KPOINTS,INCAR} ./
cat > POSCAR <<!
STO
$i
3.905 0.000 0.000
0.000 3.905 0.000
0.000 0.000 3.905
Sr  Ti  O
 1   1  3
Direct
0.0 0.0 0.0
0.5 0.5 0.5
0.0 0.5 0.5
0.5 0.0 0.5
0.5 0.5 0.0 
!
yhbatch -N 1 -n 24 -p bigdata ./vasp.sh
cd ..
done

After calculations, we use bash to obtain the results:

for i in $(seq 0.970 0.005 1.030); do cd bm$i; grep ''