`IBRION`= `-1 | 0 | 1 | 2 | 3 | 5 | 6 | 7 | 8 | 44`

Default: | ||

IBRION= |
-1 | for NSW=0 or NSW=1 |

= | 0 | else |

`IBRION` determines how the ions are updated and moved. For `IBRION`=0,
a molecular dynamics is performed, whereas all other algorithms are
destined for relaxations into a local energy minimum.
For difficult relaxation
problems it is recommended to use the conjugate gradient algorithm
(`IBRION`=2), which presently possesses the most reliable backup routines.
Damped molecular dynamics (`IBRION`=3) are often useful when starting
from very bad initial guesses. Close to the local minimum
the RMM-DIIS (`IBRION`=1) is usually the best choice.
`IBRION`=5 and `IBRION`=6 are using finite differences to
determine the second derivatives (Hessian matrix and phonon frequencies),
whereas `IBRION`=7 and `IBRION`=8 use density functional
perturbation theory to calculate the derivatives.

`IBRION=-1``IBRION`=0`IBRION`=1`IBRION`=2`IBRION`=3`IBRION`=5 and`IBRION`=6`IBRION`=7 and`IBRION`=8`IBRION`=44`IBRION`some general comments (`ISIF`,`POTIM`)

N.B. Requests for support are to be addressed to: vasp.materialphysik@univie.ac.at