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["Anglade Pierre-Matthieu" <anglade@gmail.com>]

Hello,

Sometimes the CG of WF have trouble converging ; especially for
systems requiring very large ecut. In those case since the wave
functions do not converge accurately the potential can't converge. To
solve this you have to resort to an increase of "nline". nline=15 is a
very safe value. Also you may increase nnsclo.

A very different problem could be a stong change of the susceptibility
matrix has your wavefunctions converges. In this case you will also
see oscillation of the residuals (vres2)  yet wit converged
wavefunctions (residm) int his case you'd better use preconditioning
(iprcel) and/or better mixing (iscf 7 and increased npulayit).

regards

PMA

On Tue, Jul 15, 2008 at 1:08 PM,  <tomblister@hotmail.com> wrote:
> Dear all,
>
>  During my calculation for the first derivative of the energy, after many
> iteration steps, the potential residual begins to fluctuate. It has been 
> found
> that , due to the 'log file', this potential-based CG line minimization has
> trouble to converge. What should I do to get rid of this trouble?  Should I
> raise 'nband', 'ecut' or what?
>   Longing for your reply. Thanks a lot.
>
> Sincerely,
> tom
>



-- 
Pierre-Matthieu Anglade