[Octopus-notify] svn commit: r2819 - trunk/src by xavier

[octopus-notify at tddft.org]

      Author: xavier
        Date: Sun Apr  8 23:06:14 2007
New Revision: 2819
   Changeset: http://www.tddft.org/trac/octopus/changeset/2819

Modified:
   trunk/src/epot.F90

Log:
Implemented the option of calculating the forces derivating the
wavefuncions rather than potential for non-local pseudopotentials.

I have made some tests, and using the derivatives of the wavefunctions
gives much better forces. It reduces the eggbox effect quite a few (to
about one third of the amplitude for N_2 with 0.5 [b] spacing) and the
convergence of the forces with respect to the spacing is faster and
smoother.

Besides, the code is simpler as the derivatives of the potentials are
not required. 

This is not the default, if you want to test it use:

forces=derivate_wavefunctions