[CP2K-user] SCF does not converge for a single atom of cerium

[Matt W]

Couple of comments. This is actually a rather difficult calculation to get 
correct - the full solid state calcs will probably me much easier to 
converge.
(i) your grid cuttoff is probably far to low for a q30 pseudo. You could 
also try uing GAPW method (METHOD GAPW in the QS section)
(ii) Your cell is probably too small for the MT poisson solver try 
increasing the size of the cell. WAVELET solver may be more efficient for 
atomic calcs.
(iii) ALPHA might be too big - try reducing it. Maybe then restart and 
increase a little, or try OT method.
Matt

On Monday, March 22, 2021 at 2:08:15 PM UTC jona... at gmail.com wrote:

>
> Dear cp2k developers,
>  I am trying to test the calculation using a single atom of cerium. The 
> coordinates should be ok, I am using a single atom at the origin of a box 
> of 5 A of side length. Also both basis set and pseudopotential should be 
> ok, I have found them in the data directory. I do not understand why the 
> SCF does not converge. Surely, there is an error of mine but I cannot see 
> it. I have put the muliplicity to 3, because in its electronic 
> configuration Ce has 2 unpaired. electrons. This is my input.
> &GLOBAL
>   PROJECT Ce
>   RUN_TYPE ENERGY
>   PRINT_LEVEL LOW
> &END GLOBAL
> &FORCE_EVAL
>   METHOD QS
>   &DFT
>     BASIS_SET_FILE_NAME BASIS_MOLOPT_UCL
>     POTENTIAL_FILE_NAME GTH_POTENTIALS
>     CHARGE 0
>     MULTIPLICITY 3
>     &MGRID
>       CUTOFF 550
>       REL_CUTOFF 80
>     &END MGRID
>     &QS
>       EPS_DEFAULT 1.0E-12
>       EXTRAPOLATION PS
>       EXTRAPOLATION_ORDER 3    
>     &END QS
>    &SCF
>       SCF_GUESS RESTART
>       EPS_SCF 1.0E-7
>       MAX_SCF 500
>       &MIXING T
>         METHOD BROYDEN_MIXING
>         ALPHA 0.4
>         NBROYDEN 8
>       &END MIXING
>       
>       &DIAGONALIZATION
>         ALGORITHM STANDARD
>       &END DIAGONALIZATION
>     &END SCF
>    &XC
>        DENSITY_CUTOFF     1.0000000000000000E-10
>        GRADIENT_CUTOFF     1.0000000000000000E-10
>        TAU_CUTOFF     1.0000000000000000E-10
>        &XC_FUNCTIONAL  NO_SHORTCUT
>         &PBE
>             PARAMETRIZATION ORIG
>         &END PBE
>        &END XC_FUNCTIONAL
>      &END XC  
>     &POISSON
>       PERIODIC NONE
>       POISSON_SOLVER MT
>     &END POISSON
>   &END DFT
>   &SUBSYS
>     &CELL
>       ABC 5. 5. 5.
>       PERIODIC NONE
>     &END CELL
>     &COORD
>     Ce 0.00 0.00 0.00
>     &END COORD
> &KIND Ce
>       ELEMENT   Ce
>       BASIS_SET DZVP-MOLOPT-SR-GTH-q30
>       POTENTIAL GTH-PBE-q30
>     &END KIND
> &END SUBSYS
> &END FORCE_EVAL
> Have a nice day,
> Jonathan
>
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