Setting correct cutoff/convergence criteria

Matt W mattwa... at gmail.com
Mon Jul 10 18:48:55 CEST 2017


Hi,

there are quite a few things that could be improved in your input, but the 
most significant problem is probably

   EXTRAPOLATION USE_GUESS

This means that after every step it starts again from an atomic guess, 
which is very inefficient. By default CP2K extrapolates from the density 
matrix of the previous steps.

Also, 900 Ry is a very expensive cutoff (might be needed for some elements 
with GPW). Change to METHOD GAPW in &QS and reduce the cutoff to ~300 Ry.

Mixing and broyden optimizer will be moderately inefficient for insulators, 
but the above are probably the biggest things.

Hope that helps,

Matt

On Thursday, July 6, 2017 at 6:31:57 PM UTC+2, ashish dabral wrote:
>
> Hi,
>
> I am using cp2k for geometry optimization (GEO_OPT only). I have a system 
> with almost 300 atoms(40x25x11 CELL). Even though cp2k is really fast, it 
> seems
> like here it is taking too much time as I have to wait almost 2 weeks to 
> get it to converge with 12 cores (it does converge!) and a gamma point 
> calculation.
> I am wondering if my cut-off/convergence values are ok. I realized that 
> the GEO_OPT parameter section was missing in the MOTION section but I assume
> then that the default values were used. There is a variety of atoms in the 
> complex (Si, C, Mo, Br etc.). Is it normal then, given the below setup, to 
> consume 
> so much time? A complete input is not possible to attach but I am 
> attaching the file showing different parameters: 
>
> &FORCE_EVAL
>   METHOD QS
>    &DFT
>     MULTIPLICITY  1
>     CHARGE  0
>     BASIS_SET_FILE_NAME /BASIS_MOLOPT
>     POTENTIAL_FILE_NAME /GTH_POTENTIALS
> *    SURFACE_DIPOLE_CORRECTION TRUE*
> *    SURF_DIP_DIR Z*
>     &QS
>       METHOD GPW
>       EXTRAPOLATION USE_GUESS
>     &END QS
>     &MGRID
>       CUTOFF 900
>       REL_CUTOFF 60
>     &END MGRID
>     &PRINT
>       &MO OFF
>       &END MO
>        &PDOS DEBUG 
>           NLUMO 5
>        &END PDOS
>     &END PRINT
>     &SCF
>       SCF_GUESS ATOMIC
>       MAX_SCF 400
>       ADDED_MOS 200
>       &DIAGONALIZATION T
>         ALGORITHM STANDARD
>       &END DIAGONALIZATION
>       &MIXING T
>         NBUFFER 4
>         BETA 1.25
>         ALPHA 0.2
>         METHOD BROYDEN_MIXING
>       &END MIXING
>       &PRINT
>         &RESTART ON
>         &END RESTART
>       &END PRINT
>       &SMEAR ON
>         METHOD FERMI_DIRAC
>         ELECTRONIC_TEMPERATURE [K] 300
>       &END SMEAR
>     &END SCF
>     &XC
>       &XC_FUNCTIONAL PBE
>        * &PBE*
> *          PARAMETRIZATION ORIG*
> *        &END PBE*
>       &END XC_FUNCTIONAL
>       *&VDW_POTENTIAL                                                     
>                                 *
> *        POTENTIAL_TYPE PAIR_POTENTIAL                                     
>                                   *
> *        &PAIR_POTENTIAL                                                   
>                                                  *
> *            TYPE DFTD3                                                   
>                                *
> *            REFERENCE_FUNCTIONAL PBE                                     
>                                   *
> *            R_CUTOFF  10.0                                               
>                                     *
> *            PARAMETER_FILE_NAME /dftd3.dat                       *
> *            SCALING 0.0                                                   
>                                       *
> *        &END PAIR_POTENTIAL                                               
>                                        *
> *      &END VDW_POTENTIAL *
>     &END XC
>   &END DFT
>   &PRINT
>       &STRESS_TENSOR ON
>       &END STRESS_TENSOR
>       &FORCES ON
>       &END FORCES
>   &END PRINT 
> &END FORCE_EVAL
> &MOTION
>     &CELL_OPT
>       OPTIMIZER BFGS
>       MAX_DR 0.005
>       MAX_ITER 100
>       EXTERNAL_PRESSURE 0
>       MAX_FORCE 0.0004
>       RMS_DR 0.002
>       PRESSURE_TOLERANCE 100
>       RMS_FORCE 0.001
>       TYPE DIRECT_CELL_OPT
>     &END CELL_OPT                  
>   &PRINT 
>       &TRAJECTORY
>           FORMAT PDB
>       &END TRAJECTORY
>   &END PRINT
> &END MOTION               
>
> Thanks for any inputs.
>
>
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