[Pw_forum] convergence of SCF calculation of C6H8

[Axel Kohlmeyer]

On Fri, Nov 2, 2012 at 7:22 PM, Ruibin Liu <rainbee1988 at gmail.com> wrote:

> Hi all,
>
> I tried to do a scf calculation of C6H8 (CH2CHCHCHCHCH2) with the
> optimized structure:
> 6 -0.331356 1.896930 0.000000
> 6 0.315401 3.090807 0.000000
> 1 -1.423469 1.885035 0.000000
> 1 -0.225850 4.033166 0.000000
> 1 1.402796 3.149961 0.000000
> 6 0.331356 0.596764 0.000000
> 6 -0.331356 -0.596764 0.000000
> 1 1.423645 0.599232 0.000000
> 6 0.331356 -1.896930 0.000000
> 1 -1.423645 -0.599232 0.000000
> 6 -0.315401 -3.090807 0.000000
> 1 1.423469 -1.885035 0.000000
> 1 0.225850 -4.033166 0.000000
> 1 -1.402796 -3.149961 0.000000
> I have changed the mixing beta several times and also adjusted some
> coordinates to break symmetry, but the calculation still cannot converge.
> What else should I pay attention to?
>

everything. ;-)

there is far to little information (and coordinates don't really help much),
to make a qualified statement. if i would do a wild guess, i'd suggest
to check if the cell is large enough. atoms might come too close
due to PBC. is this supposed to be an isolated or periodic system?

axel.



>
> Thanks,
> Ruibin
> --
> *Liu, Ruibin*
> Department of Chemistry
> Duke University
> Durham, NC, 27708
>
>
>
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-- 
Dr. Axel Kohlmeyer  akohlmey at gmail.com  http://goo.gl/1wk0
International Centre for Theoretical Physics, Trieste. Italy.
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