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7.20 POTIM-tag

 

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For IBRION=1,2 or 3, POTIM serves as a scaling constant for the forces.

Default
if IBRION=0 (MD) no default, user must supply this value
if IBRION=1,2,3 (relaxation) 0.5

POTIM supplies the time step for an ab-initio molecular dynamics (IBRION=0), and must be entered by the user for all MD simulations.

In addition POTIM severs as a ``scaling constant'' in all minimization algorithms (quasi-Newton, conjugate gradient, and damped molecular dynamics). Especially the Quasi-Newton algorithm is sensitive to the choice of this parameter (see section IBRION 7.19).



MASTER USER VASP
Mon Mar 29 10:38:29 MEST 1999