[Pw_forum] Force criteria for relaxation

[Guido Fratesi]

Il 04/13/2012 12:32 AM, Payam Norouzzadeh ha scritto:

> The maximum number of steps has been reached.
>   End of BFGS Geometry Optimization

Then, your system is either
  1) lowering energy and forces rather slowly
  2) unable to find the local energy minimum and wandering around

It could help to have a look if:
  i) is the total energy decreasing between the various BFGS steps?
  ii) are forces decreasing?

If (not (i)) there might be some difficulty in the minimization 
procedure, but if (i) and (not(ii)) you could have started far from the 
minimum in a system with a shallow potential energy surface.

Best,
Guido

-- 
Guido Fratesi

Dipartimento di Scienza dei Materiali
Universita` degli Studi di Milano-Bicocca
via Cozzi 53, 20125 Milano, Italy