Dear Matthias,<div><br /></div><div>Thank you for the clarification, it does make sense when you put it like that. Could you perhaps clarify in what situation a wavefunction restart file might be available and how you would enable using this as a guess? I'm guessing you don't just mean when you restart an already finished or half-completed calculation, right?</div><div><br /></div><div>Best regards,</div><div>Léon<br /><br /></div><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Tuesday, 20 June 2023 at 16:25:37 UTC+2 Krack Matthias 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;"> <div lang="en-CH" link="blue" vlink="purple" style="word-wrap:break-word"> <div> <p class="MsoNormal"><span lang="DE-CH" style="font-size:11.0pt">Dear Léon<u></u><u></u></span></p> <p class="MsoNormal"><span lang="DE-CH" style="font-size:11.0pt"><u></u> <u></u></span></p> <p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">The timings appear reasonable to me. The run time for a small unit cell with just 12 atoms using a moderate number of k points can be much faster than a Gamma point calculation for a system with 600 atoms. The timings might get a bit closer when a wavefunction restart file is available.<u></u><u></u></span></p> <p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><u></u> <u></u></span></p> <p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Best<u></u><u></u></span></p> <p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><u></u> <u></u></span></p> <p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt">Matthias<u></u><u></u></span></p> <p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt"><u></u> <u></u></span></p> <div> <div></div></div></div></div><div lang="en-CH" link="blue" vlink="purple" style="word-wrap:break-word"><div><div><div> <div style="border:none;border-top:solid #b5c4df 1.0pt;padding:3.0pt 0cm 0cm 0cm"> <p class="MsoNormal" style="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"><a href data-email-masked rel="nofollow">cp...@googlegroups.com</a> <<a href data-email-masked rel="nofollow">cp...@googlegroups.com</a>> on behalf of Léon Luntadila Lufungula <<a href data-email-masked rel="nofollow">Leon.luntad...@uantwerpen.be</a>><br> <b>Date: </b>Tuesday, 20 June 2023 at 15:09<br> <b>To: </b>cp2k <<a href data-email-masked rel="nofollow">cp...@googlegroups.com</a>><br> <b>Subject: </b>[CP2K:18941] Re: k-points vs. supercell approach<u></u><u></u></span></p> </div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">Dear all,<u></u><u></u></span></p> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt"><u></u> <u></u></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">I am currently continuing with k-point sampling as this method is much faster than the supercell calculations. However, I still don't quite understand why/how this is the case... On most of the posts I read on this forum, people state that the supercell approach should preferably be used as this is the standard in CP2K, so I don't understand why there is such a large difference in favor of k-point sampling in my case. Could anyone confirm/deny that this could be normal behaviour? I still would prefer to use the supercell approach as it has more functionalities, but I can't consider it a valid option if the computational cost is so much larger than the k-points approach...<u></u><u></u></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt"><u></u> <u></u></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">Kind regards,<u></u><u></u></span></p> </div> <div> <p class="MsoNormal" style="margin-right:0cm;margin-bottom:12.0pt;margin-left:36.0pt"> <span style="font-size:11.0pt">Léon<u></u><u></u></span></p> </div> <div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">On Monday, 19 June 2023 at 14:18:48 UTC+2 Léon Luntadila Lufungula wrote:<u></u><u></u></span></p> </div> <blockquote style="border:none;border-left:solid #cccccc 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm"> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">Dear CP2K community,<u></u><u></u></span></p> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt"><u></u> <u></u></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">I'm quite new to CP2K and I am trying to build my input files step-by-step to eventually do calculations on modified surfaces. Currently I'm still doing single point calculations on my bulk structure (anatase TiO2) to optimize the calculation parameters. I have already converged the values of the CUTOFF and REL_CUTOFF parameters and was now looking at comparing k-point sampling to gamma point calculations within the supercell approach. <u></u><u></u></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt"><u></u> <u></u></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">I was initially thinking about using the supercell approach as some things are not yet implemented for k-points, such as the OT method for example, but I noticed that supercell calculations are considerably slower than k-point calculations. I have attached the input and output files for both approaches for the largest cell/k-mesh I have used, which is 5x5x2. The k-point calculation only took 14.342s, whereas the supercell calculation took a whopping 649.442s...<u></u><u></u></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt"><u></u> <u></u></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">So my question is if I should just continue with k-points sampling or if there is something wrong with my inputs which results in the large difference in calculation time? The k-point calculation also throws a warning "*** WARNING in cryssym.F:165 :: Symmetry library SPGLIB not available ***", but I also don't know if this may be the reason for the discrepency or if I may ignore this warning.<u></u><u></u></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt"><u></u> <u></u></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">Any help would be greatly appreciated!<u></u><u></u></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt"><u></u> <u></u></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">Kind regards,<u></u><u></u></span></p> </div> <div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">Léon<u></u><u></u></span></p> </div> </blockquote> </div> </div></div></div></div><div lang="en-CH" link="blue" vlink="purple" style="word-wrap:break-word"><div><div><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 data-email-masked rel="nofollow">cp2k+uns...@googlegroups.com</a>.<br> To view this discussion on the web visit <a href="https://groups.google.com/d/msgid/cp2k/3e2ebd58-9a77-45b2-8d4a-204fd049bae3n%40googlegroups.com?utm_medium=email&utm_source=footer" target="_blank" rel="nofollow" data-saferedirecturl="https://www.google.com/url?hl=en-GB&q=https://groups.google.com/d/msgid/cp2k/3e2ebd58-9a77-45b2-8d4a-204fd049bae3n%2540googlegroups.com?utm_medium%3Demail%26utm_source%3Dfooter&source=gmail&ust=1687358115121000&usg=AOvVaw1iFwhbTGxn9uJgTgMsFIVx"> https://groups.google.com/d/msgid/cp2k/3e2ebd58-9a77-45b2-8d4a-204fd049bae3n%40googlegroups.com</a>.<u></u><u></u></span></p> </div> </div> </div> </div> </blockquote></div> <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/096c9e55-90b0-45da-928e-3468603429abn%40googlegroups.com?utm_medium=email&utm_source=footer">https://groups.google.com/d/msgid/cp2k/096c9e55-90b0-45da-928e-3468603429abn%40googlegroups.com</a>.<br />