<div dir="ltr"><div dir="ltr">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:<blockquote class="gmail_quote" style="margin:0;margin-left:0.8ex;border-left:1px #ccc solid;padding-left:1ex">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: <a rel="nofollow">hut...@chem.uzh.ch</a> Winterthurerstrasse 190 CH-8057 Zürich, Switzerland --------------------------------------------------------------- -----<a rel="nofollow">cp...@googlegroups.com</a> wrote: -----To: <a rel="nofollow">cp...@googlegroups.com</a> From: Juha Ritala Sent by: <a rel="nofollow">cp...@googlegroups.com</a> 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? </blockquote></div></div>