[CP2K-user] [CP2K:18203] Non-physical pressure behavior for non-local vdW functionals

Vyacheslav Bryantsev vyacheslav.bryantsev at gmail.com
Wed Dec 14 18:50:47 UTC 2022

Dear CP2K Developers,

I would like to follow up on unphysical stress tensor from AIMD using the 
van der Waals density functionals (e.g., optB88-vdW, optB86b-vdW).
The input file we use (attached in the previous emails) works perfectly 
fine for PBE-D3, SCAN, and SCAN-D3, which implies some problems with stress 
tensor computations in CP2K using the van der Waals density functionals.

Thank you,
Vyacheslav Bryantsev

On Thursday, December 1, 2022 at 6:38:27 PM UTC-5 ldgib... at gmail.com wrote:

> Hi Prof. Hutter,
> Thank you for your suggestion. We ran that DEBUG job with the input you 
> provided for optB86b-vdW. In the output, it compares the stress tensor 
> computed numerically and analytically, which showed that the two methods 
> gave the same result (within error). I have attached the output file from 
> that DEBUG job for reference. I have also included an xyz file for the 
> system we are looking at for any testing.
> We also discovered that we were running the SCAN-RVV10 calculations 
> without actually including the non-local vdW corrections from RVV10. So in 
> the figure I previously attached, the plot labeled "SCAN-RVV10" was 
> actually showing the pressures from SCAN without any dispersion 
> corrections. Therefore, we only see this non-physical behavior when using 
> non-local vdW functionals and showed that it is not attributed to the 
> method of computing the stress tensor (i.e., numerical vs analytical) based 
> on the DEBUG job we ran.
> We appreciate your help in identifying the source of this problem. If you 
> need any other information from us for testing, we are happy to provide it.
> Thank you,
> Luke
> On Wednesday, November 30, 2022 at 7:48:43 AM UTC-5 jgh wrote:
>> Hi 
>> difficult to say what goes wrong here. No atomic coordinates for further 
>> testing available. 
>> But I would suggest to make the following test: 
>> Debug the stress tensor using finite differences and avoid 
>> use 
>> Use the DEBUG run_type: 
>> with 
>> &DEBUG 
>> DE 0.001 
>> &END 
>> regards 
>> JH 
>> ________________________________________ 
>> From: cp... at googlegroups.com <cp... at googlegroups.com> on behalf of Luke 
>> Gibson <ldgib... at gmail.com> 
>> Sent: Monday, November 28, 2022 4:19 PM 
>> To: cp2k 
>> Subject: [CP2K:18105] Non-physical pressure behavior for non-local vdW 
>> functionals 
>> Dear developers and users, 
>> We are looking at the equilibrium density for an AlCl3 molten salt melt 
>> by measuring pressure values over 10 ps in NVT at a variety of volumes. We 
>> are comparing the pressures for a variety of functionals with various vdW 
>> corrections: PBE-D3, optB86b-vdW, optB88-vdW, SCAN-D3, and SCAN-RVV10. The 
>> data are shown in the attached plot with the mean pressure (± 1 standard 
>> deviation) for each volume (the plot for PBE-D3-smooth can be ignored). 
>> It seems optB86b-vdW, optB88-vdW, and SCAN-RVV10 are reporting unexpected 
>> behavior in the stress tensors. Both optB86b and optB88 seem to be the most 
>> "wrong" with negative pressures across the board and an unusual increase in 
>> the pressure as the system's volume is expanded (all systems have the same 
>> number of particles). SCAN-RVV10 at least follows a believable trend and 
>> isn't too far off, so it may just not be appropriate for this system. 
>> We are wondering if the stress tensor calculation is properly implemented 
>> for these non-local vdW functionals, since both PBE-D3 and SCAN-D3 are 
>> producing believable trends. 
>> For reference, I have included the input files for the 3 problematic 
>> functionals I mentioned for the volumes corresponding to V_exp in the 
>> attached plots. The versions used for each of those runs are listed below: 
>> * optB86b-vdW: CP2K-8.2 
>> * optB88-vdW: CP2K-6.1 
>> * SCAN-RVV10: CP2K-2022.2 
>> Any help or insight is appreciated! 
>> Thank you, 
>> Luke Gibson 
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