Dear Matthias,<div><br /></div><div>My AIMD calculations are on a slab wherein I keep my bottom layer fixed, but apparently REGION MASSIVE is not compatible with constraints, so I'll have to use REGION GLOBAL. Either way, thanks a lot for the detailed answer! For a novice MD practicioner as myself this is already enough information to get started! I'll try the values you suggested during my production run while keeping an eye on the temperature and pressure during the simulation; I guess when I've chosen my TIMECON too large, this will result in the system drifting away from the equilibrium values.</div><div><br /></div><div>As always, thanks a lot for all the help!</div><div><br /></div><div>Kind regards,</div><div>Léon<br /><br /></div><div class="gmail_quote"><div dir="auto" class="gmail_attr">On Tuesday 23 January 2024 at 14:21:05 UTC+1 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">Using a MASSIVE CSVR thermostat with a small TIMECON of about 50 is appropriate and efficient for equilibration. Thereafter, the TIMECON for the thermostat can be increased to 500-1000 for the sampling (production) runs and also a GLOBAL instead of a MASSIVE thermostat can be used, if possible, to reduce the impact of the thermostat on the dynamics. You will find different opinions about the absolute and relative values for the TIMECONs of thermostat and barostat in the web or literature. I suggest to use a two to five times larger TIMECON for the barostat compared to the thermostat. You have, however, to keep in mind that the appropriate (best) parameters for baro- and thermostat depend on the type of system and the selected conditions eventually.<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">HTH<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;font-family:"Aptos",sans-serif;color:black">From: </span></b><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;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, 23 January 2024 at 11:47<br> <b>To: </b>cp2k <<a href data-email-masked rel="nofollow">cp...@googlegroups.com</a>><br> <b>Subject: </b>Re: [CP2K:19801] Cons. Qty for different ensembles + Pressure fluctuation<u></u><u></u></span></p> </div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">Hi Matthias,<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></div></div></div><div lang="en-CH" link="blue" vlink="purple" style="word-wrap:break-word"><div><div><div><div> <p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt">So I started an NpT directly from the inputs you gave me with a box containing 216 water molecules. After a 300ps equilibration (plots thus starrt at 0.3 ns), the pressure fluctuations are again in the 10kbar range which is okay as you pointed out, while the average pressure is around -14 bar, so tha'ts also within the 20 bar range you mentioned. The energy drift per atom is also below 1K so everything seems to work reasonably. <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"><img width="1490" height="1789" style="width:15.5208in;min-height:18.6354in" src="https://groups.google.com/group/cp2k/attach/7718930ba853e/H2O-TIP3P_FLEXIBLE-6x6x6.mp-NPT-plots.png?part=0.1&view=1"></span></p></div></div></div></div></div><div lang="en-CH" link="blue" vlink="purple" style="word-wrap:break-word"><div><div><div><div><p class="MsoNormal" style="margin-left:36.0pt"><span style="font-size:11.0pt"><br> I'm starting my AIMD simulations as we speak, so hopefully all goes well there too. I read that it is best to do a short equilibration with a strong coupling to the thermostat (e.g. CSVR, TIMECON 20 and REGION MASSIVE), before going to a weaker coupling (e.g. CSVR, TIMECON 200 and REGION GLOBAL), but is there also a rule of thumb w.r.t. the barostat TIMECON? I regularly see TIMECON 1000, but is it useful to set it to TIMECON 100 in this early equilibration?<u></u><u></u></span></p></div></div></div></div></div><div lang="en-CH" link="blue" vlink="purple" style="word-wrap:break-word"><div><div><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">Thanks for all the help already, it really helps me a lot given the fact that I don't have a senior researcher with a lot of hands-on CP2K experience around!<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> <p class="MsoNormal"><span style="font-size:11.0pt"><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/277100be-d69a-4e36-9ef9-8cf0ac890667n%40googlegroups.com?utm_medium=email&utm_source=footer">https://groups.google.com/d/msgid/cp2k/277100be-d69a-4e36-9ef9-8cf0ac890667n%40googlegroups.com</a>.<br />