Thanks a lot for clarifying!<div><br>If would be useful if someone added these into the reference manual description.<br><br></div><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Monday, February 21, 2022 at 5:09:16 PM UTC+1 mattwa...@gmail.com wrote:<br/></div><blockquote class="gmail_quote" style="margin: 0 0 0 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">I'd need to check the exact details as I've forgotten:<div>The one inside the DFT section will operate on both electrons and atomic cores in a DFT calculation - so it pretty much corresponds to adding an electric field.</div><div>The one inside the FORCE_ENV I _think_ will only operate on cores and is mainly designed for use in the MM code or non-grid based methods. </div><div>If you are doing a DFT calc you want the one inside the DFT section, almost certainly.</div><div>Matt<br><br></div><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Monday, 14 February 2022 at 15:32:44 UTC <a href data-email-masked rel="nofollow">dr.bra...@gmail.com</a> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Dear cp2k community,<div><br></div><div>I'm confused about two EXTERNAL_POTENTIAL sections:</div><div><br></div><div><a href="https://manual.cp2k.org/cp2k-9_1-branch/CP2K_INPUT/FORCE_EVAL/EXTERNAL_POTENTIAL.html" rel="nofollow" target="_blank" data-saferedirecturl="https://www.google.com/url?hl=en&q=https://manual.cp2k.org/cp2k-9_1-branch/CP2K_INPUT/FORCE_EVAL/EXTERNAL_POTENTIAL.html&source=gmail&ust=1645662365526000&usg=AFQjCNEbQk8kGXPdEpC5EJCP8t8FRc2_ag">https://manual.cp2k.org/cp2k-9_1-branch/CP2K_INPUT/FORCE_EVAL/EXTERNAL_POTENTIAL.html</a></div><div><br></div><div>and</div><div><br></div><div><a href="https://manual.cp2k.org/cp2k-9_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/EXTERNAL_POTENTIAL.html" rel="nofollow" target="_blank" data-saferedirecturl="https://www.google.com/url?hl=en&q=https://manual.cp2k.org/cp2k-9_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/EXTERNAL_POTENTIAL.html&source=gmail&ust=1645662365526000&usg=AFQjCNG4F3My9XG5ok_dJVkxuXB5Sw6-Vw">https://manual.cp2k.org/cp2k-9_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/EXTERNAL_POTENTIAL.html</a></div><div><br></div><div>I notice differences between keywords and subsections and I want to simulate interaction of different solutes in the bulk water with the polarized graphene suface.</div><div><br></div><div>My section within the FORCE_EVAL:<br></div><div><br></div><div>  &EXTERNAL_POTENTIAL<br></div><div>    ATOMS_LIST 61..363                      # applied only on waters present in the system<br>    FUNCTION (A/B)*exp(-Z/Z0)         # potential that decays exponentially<br>    VALUES [eV] -3.0 [angstrom] 1.0 [angstrom] 6.0<br>    PARAMETERS A B Z0<br>  &END EXTERNAL_POTENTIAL<br></div><div><br></div><div>With this setup I noticed that the total energy is lower compared when no external potential is present and water molecules interact in the way I expected.</div><div><br></div><div>So, the questions are:<br>1) Is this the right way to simulate interaction with the electric field that originate from some surface, or should I employ EFIELD keywords or something similar?</div><div>2) Do I need to define EXTERNAL_POTENTIAL section within the DFT section as well, since I don't need some of the specific options there?<br></div><div>3) Could someone explain how PBC are entangled with the EXTERNAL_POTENTIAL?</div><div><br></div><div>Thanks,</div><div>Branislav</div><div><br></div></blockquote></div></blockquote></div>

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