[CP2K-user] [CP2K:16472] virial from Cp2K

[rafal gorniak]

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 *F*k 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>=sum*k*(*F*
k·*r*k)=sum*k*sumj>k(*F*kj·*r*kj). 
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 

poniedziałek, 17 stycznia 2022 o 16:22:22 UTC+1 jgh napisał(a):

> 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 : ++41 44 635 4491 <+41%2044%20635%2044%2091>
> Institut für Chemie E-mail: hut... at chem.uzh.ch 
> Universität Zürich 
> Winterthurerstrasse 190
> CH-8057 Zürich, Switzerland
> ---------------------------------------------------------------
>
> -----cp... at googlegroups.com wrote: -----
> To: "cp2k" <cp... at googlegroups.com>
> From: "rafal gorniak" 
> Sent by: cp... at googlegroups.com
> 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 
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