[CP2K:6432] Problems with GAPW + external potential
Juha Ritala
jri... at gmail.com
Thu Apr 30 11:19:19 UTC 2015
Hi Juerg,
thank you for confirming this. Is there any chance that this will be fixed
in the near future, or should I stick with GPW for the time being? I could
try and fix it myself, but as far as I understand how GAPW works,
considering the contribution from the local atomic charges is not at all
trivial.
- Juha
On Wednesday, April 29, 2015 at 2:17:45 PM UTC+3, jgh wrote:
>
> Hi
>
> yes, this is a bug. The external potential is applied to the
> charge on the plane wave grid. In GAPW only the soft part
> of the charge is on the grid and one would have to also compute
> the contributions from the local atomic charges.
>
> regards
>
> Juerg Hutter
> --------------------------------------------------------------
> Juerg Hutter Phone : ++41 44 635 4491
> Institut für Chemie C FAX : ++41 44 635 6838
> Universität Zürich E-mail: hut... at chem.uzh.ch
> Winterthurerstrasse 190
> CH-8057 Zürich, Switzerland
> ---------------------------------------------------------------
>
> -----cp... at googlegroups.com wrote: -----To: cp... at googlegroups.com
> From: Juha Ritala
> Sent by: cp... at googlegroups.com
> Date: 04/29/2015 09:52AM
> Subject: [CP2K:6432] Problems with GAPW + external potential
>
> I have had some problems when I tried to use GAPW method combined with an
> external potential. To demonstrate what seems to be the source of the
> problems, I made this simple test case with a water molecule in a constant
> external potential. Physically, the constant background potential should
> not affect the total energy of the water molecule since the molecule is
> charge neutral. The energy does change as a function of the constant
> potential when the GAPW method is used, however. You can see this in the
> attached energy vs. background potential plot. GPW method gives expected
> behaviour, the total energy stays perfectly constant when the potential is
> varied.
>
> It seems as if some part of the charge in the system is unaffected by the
> external potential in GAPW and thus the total charge is effectively
> non-zero. Is this a bug or is there some part of the implementation
> missing?
>
>
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