Hi,
I am using VASP to do elastic constants calculation.
Firstly, I optimized my crystal structure of a 2*2*2 Sn supercell. Using the CONTAR from results as the POSCAR for the elastic constants calculation.
Below is the INCAR I used.
ISTART = 0
INIWAV = 1
# Electronic SCF setup
ENCUT = 600
EDIFF = 1E-6
NELM = 400
NELMIN = 6
ISMEAR = 1
SIGMA = 0.1
GGA = PE
# Elastic constant
IBRION = 6
ISIF = 3
NFREE = 2
POTIM = 0.015
# Ionic relaxation
EDIFFG = -0.001
NSW = 1000
After trying for different Kpoints. (335, 446,557,666,668,888) (Gamma)
The elastic constants cannot converge. Still changing a lot.
Do I need to increase the Kpoints? Or anything wrong for my procedure?