VASP Elastic constants

INCAR file:

IBRION=6  

ISIF≥3

OUTPUT file:

SYMMETRIZED ELASTIC MODULI (kBar)

The elastic moduli for rigid ions are written after this line

ELASTIC MODULI CONTR FROM IONIC RELAXATION (kBar)

The ionic contributions

TOTAL ELASTIC MODULI (kBar)

The final elastic moduli including the contributions for distortions with rigid ions and from the ionic relaxations are written after this line

From: https://cms.mpi.univie.ac.at/wiki/index.php/IBRION

Other techniques: https://www.researchgate.net/post/How_VASP_calculate_elastic_constants