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henniggroup / VASPsol

Solvation model for the plane wave DFT code VASP.
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How to set the parameters in the isolated system of charged adsorbates? #77

Open itachww opened 2 years ago

itachww commented 2 years ago

Dear developers of VASPsol, I would like to use vaspsol to calculate the energy of an isolated charged system. I constructed a finite length carbon nanotube with charged peroxodisulfate ions adsorbed on it. The transition state calculations for the dissociation of this molecule were performed under vacuum, after which I want to calculate the solvation effect in a pure aqueous solution. How can I set the parameters to calculate the energy, do I just need to add EB_k = 80, LSOL = .TRUE. for the solvation calculation and IDIPOL=4? The energy (with solvation calculation) of the transition state obtained from my calculation is lower than the initial state, which is obviously unreasonable (the reaction energy barrier is around 1 eV under vacuum conditions). Is this related to the fact that the system is charged?

Here are my INCAR parameters:

PREC = Accurate ENCUT = 520.000 NPAR=4 ISYM=0 IDIPOL=4 LSOL = .TRUE. EB_K = 80 IBRION = -1 NSW = 1

ISIF = 2 NELMIN = 2 EDIFF = 1.0e-05 EDIFFG = -0.03 VOSKOWN = 1 NBLOCK = 1 NWRITE = 1 NELECT = 690.0 ISYM = 0 NELM = 200 ALGO = Fast IVDW = 12 VDW_S6 = 1.000 VDW_S8 = 0.7875 VDW_A1 = 0.4289 VDW_A2 = 4.4407 ISPIN = 1 INIWAV = 1 ISTART = 1 ICHARG = 0 LWAVE = T LCHARG = .FALSE. ADDGRID = .FALSE. ISMEAR = 0 SIGMA = 0.05 LREAL = Auto LSCALAPACK = .FALSE. RWIGS = 0.77 0.32 0.73 1.02 0.99

ericfonseca95 commented 1 year ago

Hello

My first advice would be to be sure you are accounting for the FERMI_SHIFT of your system. Since your system is charged, vaspsol will compute the shift of the fermi level due to the solvation effects. Check your OSZICAR output for this value. Let me know if this resolves your issue.

Eric