[CP2K-user] [CP2K:19009] Re: drastic change in pressure on changing smoothing

[Jürg Hutter]

Hi

disclosure: I never use the 'smoothing options' myself, so I don't have first hand experience.

Smoothing changes the density independently from the atomic positions. As long as the
functional derivatives are consistent, so will be the nuclear forces.
For the stress tensor this is no longer true as the stress depends on the cell vectors and so
do the grid points involved in smoothing. This part of the derivative is apparently not implemented.

I don't like smoothing as it 'changes' the functional from Exc[rho] to Exc[f(rho)] with unknown
consequences on physical properties.

regards
JH

________________________________________
From: cp2k at googlegroups.com <cp2k at googlegroups.com> on behalf of Vyacheslav Bryantsev <vyacheslav.bryantsev at gmail.com>
Sent: Tuesday, June 27, 2023 5:57 PM
To: cp2k
Subject: Re: [CP2K:18994] Re: drastic change in pressure on changing smoothing


Dear CP2K Developers,

If the stress tensor with "smoothing" is not currently correct, I am writing to ask if the forces on individual atoms are still correct and those can be used to fit the machine learning potential for running NPT simulations.
I am asking because we did the DeepMD fitting with and without "smoothing" and it seems that only without "smoothing" we were able to reproduce the trend in the experimental densities as a function of the temperature. Is not getting the correct stress tensor has something to do with not getting the correct densities with DeepMD? Please advise.


Thank you,
Vyacheslav Bryantsev
ORNL

On Monday, February 24, 2020 at 3:40:42 AM UTC-5 Sergi Ruiz-Barragan wrote:
Thanks Travis.

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