ISIF
ISIF = 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7
| Default: ISIF | = 0 | for IBRION=0 (molecular dynamics) |
| = 2 | else |
Description: ISIF determines whether the stress tensor is calculated and which principal degrees-of-freedom are allowed to change in relaxation and molecular dynamics runs.
ISIF determines whether the stress tensor is calculated. The calculation of the stress tensor is relatively time-consuming, and therefore by default switched off for ab initio molecular dynamics runs. The forces are always calculated.
In addition ISIF determines which degrees-of-freedom (ionic positions, cell volume, and cell shape) are allowed to change.
The following table shows all combinations:
ISIF calculate degrees-of-freedom forces Stress tensor positions cell shape cell volume 0 yes no yes no no 1 yes trace only yes no no 2 yes yes yes no no 3 yes yes yes yes yes 4 yes yes yes yes no 5 yes yes no yes no 6 yes yes no yes yes 7 yes yes no no yes
Related Tags and Sections
IBRION, ISIF, LEPSILON, LCALCEPS