[CP2K:6441] Problems with GAPW + external potential

[hut... at chem.uzh.ch]

Hi

unfortunately, I don't have time to look into this. 
It seems to me that for analytic potentials it wouldn't be that hard,
but for potentials read in on a grid it would need special care.

regards

Juerg
--------------------------------------------------------------
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: 04/30/2015 01:18PM
Subject: Re: [CP2K:6441] Problems with GAPW + external potential

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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[attachment "E_vs_V_GAPW_and_GPW.pdf" removed by Jürg Hutter/at/UZH]

[attachment "H2O_constant_extpot_GPW.inp" removed by Jürg Hutter/at/UZH]

[attachment "H2O_constant_extpot_GPW.out" removed by Jürg Hutter/at/UZH]

[attachment "H2O_constant_extpot_GAPW.inp" removed by Jürg Hutter/at/UZH]

[attachment "H2O_constant_extpot_GAPW.out" removed by Jürg Hutter/at/UZH]





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