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I am trying to do MBJLDA calculation for bandstructure for WS2 monolayer unit cell using VASP and following the method provided here : Band Structure mBJ-LDA using Vasp, but I am getting an error message. The INPUTS are below:

INCAR:

ENCUT=600
PREC = Accurate
EDIFF=1E-6
NELM=300
ISMEAR=-5

###MBJ:
METAGGA=MBJ
LASPH=.TRUE.
LMAXMIX=4
GGA=CA

LDA POTCAR:

  PAW W_pv 06Nov2007                     
   TITEL  = PAW W_pv 06Nov2007
  PAW S 27Mar2009                        
   TITEL  = PAW S 27Mar2009

POSCAR:

 W2S4                                   
   1.00000000000000     
     3.1912863255000001    0.0000000000000000    0.0000000000000000
    -1.5956425563000001    2.7637348281000000    0.0000000000000000
     0.0000000000000000    0.0000000000000000   20.1269199999999984
   W    S 
     1     2
Direct
  0.6666670084824631  0.3333329922369330  0.5000000000000000
  0.3333330949386806  0.6666670699615054  0.4218851941843354
  0.3333330949386806  0.6666670699615054  0.5781148058156645
 
  0.00000000E+00  0.00000000E+00  0.00000000E+00
  0.00000000E+00  0.00000000E+00  0.00000000E+00
  0.00000000E+00  0.00000000E+00  0.00000000E+00

The calculations was based on SCF-PBE WAVECAR. ERROR

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1 Answer 1

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I assume that:

For monolayer, it is very hard/tricky to converge at MBJ self-consistent calculation. Usually, one possible way is you can obtain the CMBJ=XXX from its bulk counterpart.

I have tried this but get unsatisfactory result:

  • Bulk WS2 (SOC is ignored!):

    • PBE band: enter image description here

    • MBJ band: enter image description here

      grep CMBJ OUTCAR ====> CMBJ=1.2327
      
  • Monolayer WS2:

    • PBE result: enter image description here

    • MBJ result: enter image description here

      INCAR

       ### Read PBE wavefunction
       ISTART=1
       ICHARG=0
       ENCUT=400
       EDIFF=1E-6
       NELM=300
       ISMEAR=-5
      
       ###MBJ:
       METAGGA=MBJ
       LASPH=.TRUE.
       LMAXMIX=4
       GGA=CA
       CMBJ=1.2327
      

This unsatisfactory result may be related to the badly converged MBJ self-consistent calculation. Unfortunately, I haven't found any solutions for this (still trying...).

By the way, the system contains only three atoms, why not using the HSE06 method?

Hope it helps.

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  • $\begingroup$ I am also getting the same error for a bulk material, my system is quite big. I am not sure how did you fix the question asked by Chi kou. Like I know that setting a value for CBMJ helps with convergence but I do not have any value for my specific case and I have tried a few values none of which helo this issue ? Furthermore, I do not get this error in PBE so this should be something related to mBJ only. $\endgroup$
    – Chan
    Commented Sep 7, 2022 at 9:20
  • $\begingroup$ So actually my issue went away if I simply did not put ISMEAR = -5 in my INCAR. But very confused as to why this problem was happening in the first place. $\endgroup$
    – Chan
    Commented Sep 7, 2022 at 10:23

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