SCF run NOT converged

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eitan eidelstein

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Nov 21, 2022, 8:15:14 AM11/21/22
to cp2k
Hi,
This calculation is not converging.
I will be delighted for any sugestion.
Thanks, 
Eitan.

&FORCE_EVAL
  METHOD Quickstep              
  &DFT
    BASIS_SET_FILE_NAME  BASIS_MOLOPT_UZH
    #BASIS_SET_FILE_NAME BASIS_SET
    #POTENTIAL_FILE_NAME  POTENTIAL
    POTENTIAL_FILE_NAME POTENTIAL_UZH
    CHARGE 0
    SPIN_POLARIZED .TRUE. # SPIN_POLIRIZED
    MULTIPLICITY 1
    RELAX_MULTIPLICITY 0.1
    &MGRID
      CUTOFF 200
    &END MGRID
    &POISSON                
      PERIODIC XYZ
      poisson_solver periodic
    &END POISSON
    &SCF
         SCF_GUESS ATOMIC
         EPS_SCF 1.0E-10
         MAX_SCF 1000
         ADDED_MOS 100
         &DIAGONALIZATION
            ALGORITHM STANDARD
            EPS_ADAPT 0.001
         &END DIAGONALIZATION
         &SMEAR  ON
            METHOD FERMI_DIRAC
            ELECTRONIC_TEMPERATURE [K] 300
         &END SMEAR

       &MIXING
          METHOD BROYDEN_MIXING
          ALPHA 0.2
          BETA 1.5
          NBROYDEN 8
       &END MIXING

    &END SCF
    &XC         
      &XC_FUNCTIONAL PBE
      &END XC_FUNCTIONAL
    &END XC
    &KPOINTS
       SCHEME  MONKHORST-PACK  30 30 30  
    &END KPOINTS

    &PRINT
       &DOS
          FILENAME dos
          NDIGITS 14
       &END DOS
       &PDOS
          FILENAME pdos
          # print all projected DOS available:
          NLUMO -1
          # split the density by quantum number:
          COMPONENTS .TRUE.
       &END PDOS
    &END PRINT
  &END DFT
  &SUBSYS
    &PRINT
      &SYMMETRY
        ALL
      &END
    &END PRINT
    &CELL  # 8.104532945 4.0522664725
      A [bohr] 8.104532945  4.0522664725 4.0522664725
      B [bohr] 4.0522664725 8.104532945  4.0522664725
      C [bohr] 4.0522664725 4.0522664725 8.104532945
      PERIODIC XYZ
    &END CELL
    &KIND Co1
      ELEMENT Co
      BASIS_SET DZVP-MOLOPT-PBE-GTH-q17
      #BASIS_SET DZV-GTH-PADE
      #POTENTIAL GTH-PBE
      POTENTIAL GTH-PBE-q17
      #&BS
      #  &ALPHA
      #  &END
      #  &BETA
      #  &END
      #&END BS
      #MAGNETIZATION 1.0
    &END KIND
    &KIND Co2
      ELEMENT Co
      BASIS_SET DZVP-MOLOPT-PBE-GTH-q17
      #BASIS_SET DZV-GTH-PADE
      #POTENTIAL GTH-PBE
      POTENTIAL GTH-PBE-q17
      #&BS
      #  &ALPHA
      #  &END
      #  &BETA
      #  &END
      #&END BS
      #MAGNETIZATION -1.0
    &END KIND

    &KIND O
      ELEMENT O
      BASIS_SET DZVP-MOLOPT-PBE-GTH-q6
      #BASIS_SET DZVP-GTH-PADE
      #POTENTIAL GTH-PBE
      POTENTIAL GTH-PBE-q6
    &END KIND
    &COORD
      SCALED
        Co1 0.0 0.0 0.0
        Co2 0.5 0.5 0.5
        O 0.25 0.25 0.25
        O 0.75 0.75 0.75
    &END COORD

  &END SUBSYS
&END FORCE_EVAL
&GLOBAL
  PROJECT CoO
  RUN_TYPE ENERGY
  PRINT_LEVEL MEDIUM
&END GLOBAL

Krack Matthias (PSI)

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Nov 21, 2022, 11:26:18 AM11/21/22
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Hi

  • try a supercell, e.g. 3x3x3 (MULTIPLE_UNIT_CELL keyword in &CELL and &TOPOLOGY section), instead of k points
  • Increase the cutoff to 400 Ry
  • Increase the smearing temperature if needed

 

HTH

 

M.

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eitan eidelstein

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Nov 22, 2022, 5:43:22 AM11/22/22
to cp2k
Thanks, I will try those.
Can you explain why MULTIPLE_UNIT_CELL 3 3 3 is helping for PERIODIC XYZ? and why 3 instead of 2?

Krack Matthias (PSI)

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Nov 22, 2022, 6:03:31 AM11/22/22
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A supercell with at least ~12A in each direction is most likely more efficient than a primitive cell with a large number of k points. CP2K/Quickstep employs localized Gaussian functions as basis set and their interaction range is not impacted by the cell size. Therefore many computational steps do not benefit from a small cell. On the other hand, several features are not yet available with k points and thus, if k points are dispensable, more feature are available.

eitan eidelstein

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Nov 22, 2022, 7:55:07 AM11/22/22
to cp2k
So, your suggestion is not to use k points at all (or only Gamma point)?

Krack Matthias (PSI)

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Nov 22, 2022, 8:17:46 AM11/22/22
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That’s your decision depending on the system and the properties you are interested in, e.g. you will need k points, if you want to plot the band structure.

On the other hand, a 3x3x3 supercell is roughly equivalent to using 3x3x3 k points with the 1x1x1 cell.

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