Thank you Juerg for your answer. I’m a beginner at cp2k calculations however if you take closer my input file (inp.input) where the forces are calculated I’m using a pbc convention. I thought with the total forces Fk on particle k treated as the sum of all the forces from the other particles j in the system I will be able to calculate virial because the virial is defined as <w>=sumk(Fk·rk)=sumksumj>k(Fkj·rkj). My project is generally bias simulations, where external forces will be calculated from a different program and those forces must be added (modified) to the forces from cp2k. But the whole simulation must be applied at Npt ensemble. Best regards,Rafal <div class="gmail_quote"><div dir="auto" class="gmail_attr">poniedziałek, 17 stycznia 2022 o 16:22:22 UTC+1 jgh napisał(a): </div><blockquote class="gmail_quote" style="margin: 0 0 0 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">Hi CP2K stress tensor calculations return the derivative of the total energy wrt the cell parameters. For NPT simulations the kinetic energy part is added to account for finite temperature effects. The virial can only be calculated from the nuclear gradients under certain conditions, e.g. pair atomic forces (so not in DFT) and minimum image conditions. regards Juerg Hutter -------------------------------------------------------------- Juerg Hutter Phone : <a href="tel:+41%2044%20635%2044%2091" value="+41446354491" target="_blank" rel="nofollow">++41 44 635 4491</a> Institut für Chemie E-mail: <a href data-email-masked rel="nofollow">hut...@chem.uzh.ch</a> Universität Zürich Winterthurerstrasse 190 CH-8057 Zürich, Switzerland --------------------------------------------------------------- -----<a href data-email-masked rel="nofollow">cp...@googlegroups.com</a> wrote: ----- To: "cp2k" <<a href data-email-masked rel="nofollow">cp...@googlegroups.com</a>> From: "rafal gorniak" Sent by: <a href data-email-masked rel="nofollow">cp...@googlegroups.com</a> Date: 01/14/2022 03:06PM Subject: [CP2K:16461] virial from Cp2K Dear All, I'm trying to calculate virial for some crystal structure using cp2k. In cp2k I can calculate stress tensor is that feature is exactly virial or contain kinetic energy part (de facto it's a pressure)? I know from cp2k I can have a forces and atom positions thus I also should be able to calculate virial. am I right? With kind regards Rafal -- You received this message because you are subscribed to the Google Groups "cp2k" group. 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>. To view this discussion on the web visit <a href="https://groups.google.com/d/msgid/cp2k/c025f562-4ddb-4992-a273-43caa023384an%40googlegroups.com" target="_blank" rel="nofollow" data-saferedirecturl="https://www.google.com/url?hl=pl&q=https://groups.google.com/d/msgid/cp2k/c025f562-4ddb-4992-a273-43caa023384an%2540googlegroups.com&source=gmail&ust=1642762122102000&usg=AFQjCNFmTU2fxWk3YelOumqwfeE2y-FwHg">https://groups.google.com/d/msgid/cp2k/c025f562-4ddb-4992-a273-43caa023384an%40googlegroups.com</a>. </blockquote></div> -- You received this message because you are subscribed to the Google Groups "cp2k" group. 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>. To view this discussion on the web visit <a href="https://groups.google.com/d/msgid/cp2k/2fd5b15f-7367-4889-a63c-20329299ecc0n%40googlegroups.com?utm_medium=email&utm_source=footer">https://groups.google.com/d/msgid/cp2k/2fd5b15f-7367-4889-a63c-20329299ecc0n%40googlegroups.com</a>.