[CP2K-user] [CP2K:18105] Non-physical pressure behavior for non-local vdW functionals

[Luke Gibson]

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

-- 
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 cp2k+unsubscribe at googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/afc955e0-daad-40f4-8bce-87b08f87cb8dn%40googlegroups.com.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20221128/e130d627/attachment-0001.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: optB88-vdW_cp2k-6.1.inp
Type: chemical/x-gamess-input
Size: 3362 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20221128/e130d627/attachment-0003.inp>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: optB86b-vdW_cp2k-8.2.inp
Type: chemical/x-gamess-input
Size: 3441 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20221128/e130d627/attachment-0004.inp>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: scan-rvv10_cp2k-2022.2.inp
Type: chemical/x-gamess-input
Size: 3114 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20221128/e130d627/attachment-0005.inp>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: pressures_all_xc_separated.png
Type: image/png
Size: 137221 bytes
Desc: not available
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20221128/e130d627/attachment-0001.png>