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

Hi,

Since you are working with a relatively small system I would suggest you tu 
use
iprcel 4X instead of diemac. This will speed up your true SCF
convergence.  (For inhomogeneous systems diemac will lead energy
change to reduce without ever reaching convergency.)

If ths system keeps refusing to converge it means that there is too
many states near the Fermi energy. The solution then is to get
convergency with a small electronic temperature, treating the system
as if it was metallic (tsmaer and occopt).

regards
PMA



On 10/23/06, 张�s <zhangting1980323@gmail.com> wrote:
> Dear all:
>
>        I'm calculating phonon band of 5,5 CNT with GGA-PBE XC. I've
> optimized the CNT's sturcture to the max force 1.6e-6 Ha/Bohr.
> But when I start to perform phonon calculation, I found that the SCF dataset
> can not converge to the suggested tolvrs=1.0d-18, but to
> oscillate at about 1.0d-10. I'm testing a similar SCF calculation with LDA,
> Teter Pade XC, it seems converge well. Why does this happen? Thanks!


--
Pierre-Matthieu Anglade