[CP2K-user] CP2K 101

[Matthias Krack]

Hi Henrique

there are several issue in your input. Here are my suggestions: 

   - A cutoff of 300 Ry is too small for the Na GTH-PBE-q9. The accuracy of 
   the electron count should show that. Try 600 Ry.
   - EPS_DEFAULT should be lower than 1.0E-10, I recommend at least 1.0E-12.
   - Use at least 1.0E-6 (or less) for EPS_SCF in &OT and &OUTER_SCF or 
   switch to diagonalisation by setting &OT off, since your system is very 
   small.
   - Use BFGS as OPTIMIZER instead of CG in &CELL_OPT

HTH

Matthias

On Tuesday, 9 October 2018 18:05:01 UTC+2, Henrique Junior wrote:
>
> Hello, guys,
> To get started with CP2K I'm trying some basic experiments. As an example, 
> the CELL_OPT/GEO-OPT for NaCl (using the initial unitary cell from a .cif 
> taken from a databese on the web).
> The problem is that even this very (supposedly) simple system is not 
> converging after 2000 geometry iterations.
> Could someone check my input and provide some hints for a better 
> convergence?
> P.S.: The intention is to use something like PBE (looks like TPSS can not 
> be used for geometry opt, right?).
>
> Here is my input:
> &GLOBAL
>  PROJECT NaCl
>  RUN_TYPE CELL_OPT
>  PRINT_LEVEL LOW
> &END GLOBAL
>
> &MOTION
>   &CELL_OPT
>     KEEP_ANGLES true
>     KEEP_SYMMETRY true
>     MAX_ITER 2000
>     OPTIMIZER CG
>     TYPE DIRECT_CELL_OPT
>     EXTERNAL_PRESSURE 10000.0 0.0 0.0 0.0 10000.0 0.0 0.0 0.0 10000.0
>     PRESSURE_TOLERANCE 10000
>   &END CELL_OPT
>   &GEO_OPT
>     OPTIMIZER CG
>   &END GEO_OPT
> &END MOTION
>
> &FORCE_EVAL
>  STRESS_TENSOR DIAGONAL_ANALYTICAL
>  METHOD QS
>
>  &DFT
>
>   &QS
>     EPS_DEFAULT 1.0E-10
>     EXTRAPOLATION ASPC
>     EXTRAPOLATION_ORDER 3
>     METHOD GPW
>     PW_GRID NS-FULLSPACE
>     MAP_CONSISTENT
>   &END QS
>
>   CHARGE 0
>   MULTIPLICITY 1
>   BASIS_SET_FILE_NAME  GTH_BASIS_SETS
>   POTENTIAL_FILE_NAME  POTENTIAL
>
>   &MGRID
>     COMMENSURATE
>     CUTOFF 300
>     NGRIDS 5
>     REALSPACE
>     RELATIVE_CUTOFF 80
>    &RS_GRID
>     DISTRIBUTION_TYPE AUTOMATIC
>    &END RS_GRID
>   &END MGRID
>
>   &XC
>    &XC_FUNCTIONAL PBE
>    &END XC_FUNCTIONAL
>   &END XC
>   &SCF
>     EPS_SCF 1.0E-5
>     MAX_DIIS 4
>     MAX_SCF 500
>     SCF_GUESS RESTART
>    &OT 
>       ALGORITHM IRAC
>       ORTHO_IRAC POLY
>       ENERGY_GAP 0.001     
>       LINESEARCH 2PNT
>       MINIMIZER CG
>       PRECONDITIONER FULL_ALL
>    &END OT
>    &OUTER_SCF  T
>       EPS_SCF     1.0000000000000000E-04
>       MAX_SCF             500
>       OPTIMIZER DIIS
>    &END OUTER_SCF
>   &END SCF
>  &END DFT
>
>  &SUBSYS
>   &COORD
>     Na      0.000000    0.000000    0.000000
>     Cl     -2.810000    0.000000    0.000000
>   &END COORD
>
>     &KIND Na
>       BASIS_SET DZVP-MOLOPT-SR-GTH-q9
>       POTENTIAL GTH-PBE-q9
>     &END KIND
>     &KIND Cl
>       BASIS_SET DZVP-MOLOPT-SR-GTH-q7
>       POTENTIAL GTH-PBE-q7
>     &END KIND
>
>   &CELL
>     ABC 5.62 5.62 5.62      
>     ALPHA_BETA_GAMMA    90.00000 90.00000 90.00000      
>   &END CELL
>  &END SUBSYS
>
> &END FORCE_EVAL 
>
>
>
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