Error in BS calculation: KS energy is an abnornal value

[Parismita Borgohain]

Hello, I am trying to do BS calculation in Gd2 system but i got this error all the time. i have tried  &SCF

      SCF_GUESS ATOMIC
      EPS_SCF 1.0E-7
      MAX_SCF 1000
      CHOLESKY INVERSE
      ADDED_MOS 50
      &SMEAR ON
        METHOD FERMI_DIRAC
        ELECTRONIC_TEMPERATURE [K] 300
      &END SMEAR
      &DIAGONALIZATION
        ALGORITHM STANDARD
      &END DIAGONALIZATION
      &MIXING
        METHOD PULAY_MIXING
        PULAY_ALPHA 0.4
        NPULAY 8
      &END MIXING
    &END SCF

and  &SCF

      SCF_GUESS ATOMIC
      EPS_SCF 1.0E-5
      MAX_SCF 1000
      CHOLESKY INVERSE
      LEVEL_SHIFT 0.2
      ADDED_MOS 50
      &SMEAR ON
        METHOD FERMI_DIRAC
        ELECTRONIC_TEMPERATURE [K] 500
      &END SMEAR
      &DIAGONALIZATION
        ALGORITHM STANDARD
      &END DIAGONALIZATION
      &MIXING
        METHOD BROYDEN_MIXING
        ALPHA 0.4
        NBROYDEN 8
      &END MIXING
    &END SCF.  But I got the same error. Can anyone please suggest me some scf convergence tips.

 SCF WAVEFUNCTION OPTIMIZATION

  Step     Update method      Time    Convergence         Total energy    Change
  ------------------------------------------------------------------------------

 *******************************************************************************
 *   ___                                                                       *
 *  /   \                                                                      *
 * [ABORT]                                                                     *
 *  \___/                KS energy is an abnormal value (NaN/Inf).             *
 *    |                                                                        *
 *  O/|                                                                        *
 * /| |                                                                        *
 * / \                                                     qs_ks_methods.F:889 *
 *******************************************************************************

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[Thomas Kühne]

his is not a normal SCF convergence failure. The calculation aborts before the first SCF iteration while CP2K is building the initial Kohn–Sham energy. Therefore changing MAX_SCF, Pulay/Broyden mixing, or the electronic temperature will not fix the underlying NaN.

Please provide the complete input and the output from the beginning up to the abort, especially:

• UKS, CHARGE, and MULTIPLICITY
• both Gd &KIND sections, including the complete &BS definitions
• basis-set and pseudopotential names/files
• DFT+U and XC settings
• coordinates, cell, and Poisson periodicity
• CP2K version

As a diagnostic, first remove the &BS sections, smearing, level shift, and explicit CHOLESKY INVERSE, and try a plain UKS calculation with the default Cholesky method. If that works, the problem is in the broken-symmetry occupations.

Note that NEL in &BS specifies changes relative to the atomic reference occupation, not the final occupation. Check the “Guess for atomic kind” section in the output. Also make sure the Gd pseudopotential includes the 4f electrons in the valence. The LnPP2/q11 potentials are 4f-in-core and cannot describe opposite local 4f spin configurations.

Finally, LEVEL_SHIFT 0.2 without a unit means 0.2 Hartree, not 0.2 eV.

Once the calculation gives a finite initial energy, SCF convergence can be improved separately, for example with a smaller mixing alpha such as 0.1–0.2.

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