Thank you very much for your reply. However, I think I don't quite understand: in CP2K I can do a CELL_OPT and get the relaxed system at 0K; can I instead get the relaxed cell at a temperature of 300K? <br /><br />I could extract from the trajectory N configurations of the system at 300K and for each of these do a CELL_OPT, evaluating the volume behaviour. Does this make sense?<br /> <br />Thanks again for your time<br /><br />Simone <br /><br /><div class="gmail_quote"><div dir="auto" class="gmail_attr">Il giorno lunedì 11 dicembre 2023 alle 17:44:26 UTC+1 Thomas Kühne ha scritto:<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 style="word-wrap:break-word;line-break:after-white-space">Dear Simone Ritarossi, <div><br></div><div>just 2 comments from my side. </div><div>(i) When using CELL_OPT/TYPE MD, a MD simulation is conducted to obtain the ensemble averaged stress tensor to conduct </div><div>your cell optimization. This is not only excessively expensive (in your case a 10000 step AIMD calculation is performed for each </div><div>cell optimization step!), but in my experience is also not effective due to the inherent fluctuations in the stress tensor, in particular </div><div>when using this in conjunction with a quasi-Newton optimizer such as BFGS that tolerates noise very poorly. </div><div>(ii) In the comment of your input file you write "Performs a geometry and cell optimization at the same time. The stress tensor is </div><div>computed at every step“. If this is what you want to do simply use TYPE DIRECT_CELL_OPT instead. </div><div><br></div><div>Greetings, </div><div>Thomas Kühne</div><div><div><br><blockquote type="cite"></blockquote></div></div></div><div style="word-wrap:break-word;line-break:after-white-space"><div><div><blockquote type="cite"><div>Am 11.12.2023 um 10:17 schrieb Simone Ritarossi <<a href data-email-masked rel="nofollow">sim.ri...@gmail.com</a>>:</div><br></blockquote></div></div></div><div style="word-wrap:break-word;line-break:after-white-space"><div><div><blockquote type="cite"><div>Dear users,<br><br>I have a problem with the use of CELL_OPT at temperatures other than 0K. Following CP2K's guide (I could not find any discussions on the subject on the web), I understood that I have to 1) set the RUN_TYPE CELL_OPT, 2) define TYPE MD in the CELL_OPT section and 3) define an MD section. In the guide it says " <em style="font-family:"Times New Roman";font-size:inherit"> Two possible schemes are available: (1) Zero temperature optimization; (2) Finite temperature optimization</em> ". <br>However, I do not get the optimization. .<br>I attach here the input and output files. I cannot understand the error in the output (I cannot find anything similar on the web): the abort message is " CPASSERT failed - motion/gopt_f77_methods.F:307"<br><br><br>Thank you for your time!<br><div><br></div></div></blockquote></div></div></div><div style="word-wrap:break-word;line-break:after-white-space"><div><div><blockquote type="cite"><div>
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<span><PCH_GST_TiTe2_CELL_OPT_MD.out></span><span><PCH_GST_TiTe2_CELL_OPT_MD-MD-1.out></span><span><PCH_GST_TiTe2_CELL_OPT_MD.inp></span><span><PCH_GST_TiTe2_CELL_OPT_MD-MD-0.out></span><span><job.err></span></div></blockquote></div><br></div></div></blockquote></div>
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