Non-constant vacuum potential with dipole corrections enabled

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brennc43
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Non-constant vacuum potential with dipole corrections enabled

#1 Post by brennc43 » Fri Dec 20, 2024 12:34 pm

Hi,

I have been modelling a 4 layer thick Ag slab at the z-edge of a (4x4) supercell. When I adsorb an oxygen atom to one side of the slab, this creates a dipole which I am trying to correct for. However, when I turn on dipole corrections using the relevant tags in the INCAR, the LOCPOT file remains unchanged relative to without the dipole correction tags and the potential in the vacuum region remains sloped, not constant as it should be. I have a 15 angstrom vacuum above the adsorbed atom in the z-direction (and have tried with larger giving the same result). I'm wondering if there is a conflicting tag in my INCAR file that could be messing with this correction, as I am not seeing a 'step' in the potential in the vacuum region as I have seen is expected. In the OUTCAR file, VASP is reading and turning on the dipole correction but I do not see this result in the LOCPOT. I will attach my INCAR below, as well as an image of my cell and plot of the planar averaged electrostatic potential obtained with these INCAR settings. Any help you could provide would be much appreciated.

ISPIN = 2
GGA = BF
LUSE_VDW = .TRUE.
Zab_VDW = -1.8867
LBEEFENS = .TRUE.
ICHARG = 1

ENCUT = 500
EDIFF = 1.00e-06
EDIFFG = -0.01
LREAL = Auto
NELM = 120

NSW = 400
IBRION = 2
POTIM = 0.1
KPAR = 5
NCORE = 6

ISMEAR = 1
SIGMA = 0.2
ISIF = 2

LVHAR = .True.
LDIPOL = .True.
IDIPOL = 3

LORBIT = 11
LASPH = .TRUE.

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andreas.singraber
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Re: Non-constant vacuum potential with dipole corrections enabled

#2 Post by andreas.singraber » Fri Dec 20, 2024 1:55 pm

Hello!

Welcome to the VASP forum! Can you please add all the relevant input and output files so I can have a closer look and try to reproduce your results. There is a detailed description of what could be relevant in our forum posting guidelines (follow the link for the minimal reproducible example). It would be great if you could prepare two folders "with/without-dipole-corr" so I can quickly get to the same results you have. Thank you!!

Best regards,
Andreas Singraber


brennc43
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Re: Non-constant vacuum potential with dipole corrections enabled

#3 Post by brennc43 » Fri Dec 20, 2024 4:34 pm

Hi Andreas,

Thanks for your quick reply! Please find attached the relevant files, I couldn't include the LOCPOT as it was too large.

All the best,
Conor


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