difference in different version of POTCARs

[qiangzhu]

Dear vasp users,

I just recently test the POTCARs from different version. It seems the results are not consistent for vdw functionals. For VASP_PSEUDOS, I choose POTCAR_C from different categories, potpaw_PBE and potpaw_PBE_52_NEW.

When I did calculations for the very simple graphite structure, the calculated energy for PBE are almost consistent. Below is just a comparison for the reference:
graphite structures 4 atoms/cell
Old potpaw_PBE: -36.891 eV
new potpaw_PBE: -36.877 eV

But if I stepped to vdw-DF, with the following keywords recommended by the manual:
for optPBE-vdW,

GGA = BO
PARAM1 = 0.1833333333
PARAM2 = 0.2200000000
LUSE_VDW = .TRUE.
AGGAC = 0.0000


I obtained quite different energetics for two version of POTCARS.
Old potpaw_PBE: -37.1637 eV (optPBE-vdw)
new potpaw_PBE: -32.0297 eV (optPBE-vdw)

I also did test on some other systems. It seems that the new PBE generally gives substantially higher energy than old PBE. Can any people explain why? Shall I trust these results?

When I compared the two version of POTCARs, I noticed that most of the old POTCARs are generated with the flag
IUNSCR = 0 unscreen: 0-lin 1-nonlin 2-no

But in the new version (potpaw_PBE_52_NEW), the flag changes to
IUNSCR = 0 unscreen: 0-lin 1-nonlin 2-no

Can anyone briefly explain the difference?

Thanks in advance.

[support_vasp]

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