early termination of dynamical matrix calculation

[chwang45]

At a local minimum, I am trying to get the dynamical matrix with 24 degrees of freedom. The NSW variable, 25, is equal to the number of degrees of freedom plus one. However, vasp terminates early only after the first ionic step writing "reached required accuracy - stopping structural energy minimisation." Would anyone tell me the possible reasons and how to correct the behaviour? I changed the displacement to a bigger value, but it does not seem to help.

Thanks for your help in advance!

[andri]

It is possible that the potential surface so flat around your minima that the force doesn't rise considerably when the atoms are displaced. Try to set EDIFFG to something really small in the INCAR, e.g. EDIFFG = -1.0E-15 (or even smaller).

Andri