<html xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"> <head> <meta http-equiv="Content-Type" content="text/html; charset=us-ascii"> <meta name="Generator" content="Microsoft Word 15 (filtered medium)"> <style></style> </head> <body lang="en-CH" link="blue" vlink="purple" style="word-wrap:break-word"> <div class="WordSection1"> <p class="MsoNormal"><span lang="DE-CH" style="font-size:11.0pt;mso-fareast-language:EN-US">Hi Corrado<o:p></o:p></span></p> <p class="MsoNormal"><span lang="DE-CH" style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p> <p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">CP2K does not take advantage of symmetry for better computational efficiency. The constraints are rather meant to preserve or enforce a certain symmetry during structure relaxations, because the symmetric structure is not the exact minimum or it distorts slightly due to numerical noise. The latter is the reason why it can make sense to use the constraint KEEP_ANGLES which will keep all cell angles exactly at 90 degree, because CP2K/Quickstep is faster for orthorhombic cells. Therefore, based on the information which you provided for your system, I would apply only the constraint KEEP_ANGLES in the runs with small molecules adsorbed.<o:p></o:p></span></p> <p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p> <p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">HTH<o:p></o:p></span></p> <p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p> <p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US">Matthias<o:p></o:p></span></p> <p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p> <div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm"> <p class="MsoNormal" style="mso-margin-top-alt:0cm;margin-right:0cm;margin-bottom:12.0pt;margin-left:36.0pt"> <b><span style="font-size:12.0pt;color:black">From: </span></b><span style="font-size:12.0pt;color:black">cp2k@googlegroups.com <cp2k@googlegroups.com> on behalf of Corrado Bacchiocchi <bacchio@gmail.com><br> <b>Date: </b>Tuesday, 20 December 2022 at 09:54<br> <b>To: </b>cp2k <cp2k@googlegroups.com><br> <b>Subject: </b>[CP2K:18220] MOF cell opt with KEEP_SYMMETRY FALSE<o:p></o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">Dear Colleagues,<o:p></o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">I ask you to kindly share your experience about the following question.<o:p></o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt"><o:p> </o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">We have performed on our MOF structure the "Converge CUTOFF and REL_CUTOFF" procedure, as described in the very helpful page:<o:p></o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt"><o:p> </o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">https://www.cp2k.org/howto:converging_cutoff<o:p></o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt"><o:p> </o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">and found that, with NGRIDS 4, to reach a 1.E-7 difference with respect to the limiting value of the energy, the minimum settings are:<o:p></o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt"> <br> CUTOFF 1800<br> REL_CUTOFF 80<o:p></o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt"><o:p> </o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">We have then successfully performed CELL_OPT on a 2x2x2 supercell of our MOF with KEEP_SYMMETRY TRUE.<o:p></o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">When we use this optimized structure for a subsequent CELL_OPT with KEEP_SYMMETRY FALSE the BFGS algorithm is not able to further decrease the energy. The structure remains essentially unmodified across hundreds of steps and the optimization does not complete.<o:p></o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">I attach the input file and the guess structure and I kindly ask the following:<o:p></o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">- is it essential, for any publication quality structure, that KEEP_SYMMETRY is FALSE or is it acceptable to have this constraint in place?<o:p></o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">- more in general, for any subsequent calculation, e.g. interaction of small molecules on the surface of the MOF, Nudged Elastic Band energy path investigations, etc., is it possible/acceptable to KEEP_SYMMETRY TRUE?<o:p></o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt"><o:p> </o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">Thank you very much for your kind help<o:p></o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">Have a nice Holiday Season!<o:p></o:p></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">Corrado<o:p></o:p></span></p> </div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">-- <br> You received this message because you are subscribed to the Google Groups "cp2k" group.<br> To unsubscribe from this group and stop receiving emails from it, send an email to <a href="mailto:cp2k+unsubscribe@googlegroups.com">cp2k+unsubscribe@googlegroups.com</a>.<br> To view this discussion on the web visit <a href="https://groups.google.com/d/msgid/cp2k/14f06834-79c7-4ac8-922c-d1d6f008d27fn%40googlegroups.com?utm_medium=email&utm_source=footer"> https://groups.google.com/d/msgid/cp2k/14f06834-79c7-4ac8-922c-d1d6f008d27fn%40googlegroups.com</a>.<o:p></o:p></span></p> </div> </body> </html> <p></p> -- <br /> You received this message because you are subscribed to the Google Groups "cp2k" group.<br /> To unsubscribe from this group and stop receiving emails from it, send an email to <a href="mailto:cp2k+unsubscribe@googlegroups.com">cp2k+unsubscribe@googlegroups.com</a>.<br /> To view this discussion on the web visit <a href="https://groups.google.com/d/msgid/cp2k/ZRAP278MB082764EB47964BA52E846796F4EA9%40ZRAP278MB0827.CHEP278.PROD.OUTLOOK.COM?utm_medium=email&utm_source=footer">https://groups.google.com/d/msgid/cp2k/ZRAP278MB082764EB47964BA52E846796F4EA9%40ZRAP278MB0827.CHEP278.PROD.OUTLOOK.COM</a>.<br />