[CP2K:4549] Bulk modulus of silicon with CP2K

[leila salimi]

Dear Juerg,

Thanks for your answer.
1) the PBE value for B is 89 GPa.
2) I also tried with higher cutoff and REF_CUTOFF, but it didn't change.

&MGRID
      NGRIDS 8
      CUTOFF 500
      REL_CUTOFF  60
    &END MGRID


On Mon, Aug 12, 2013 at 2:40 PM, <hut... at pci.uzh.ch> wrote:

> Hi
>
> two things to do:
> 1) What is the official PBE value for this quantity?
> 2) Use a REF_CELL and a high enough cutoff (has to be tested)
>    in order to get a smooth enough pressure curve
>
> regards
>
> Juerg
>
> --------------------------------------------------------------
> Juerg Hutter                         Phone : ++41 44 635 4491
> Physical Chemistry Institute   FAX   : ++41 44 635 6838
> University of Zurich               E-mail:  hut... at pci.uzh.ch
> Winterthurerstrasse 190
> CH-8057 Zurich, Switzerland
> ---------------------------------------------------------------
>
> -----cp... at googlegroups.com wrote: -----
> To: cp... at googlegroups.com
> From: leila
> Sent by: cp... at googlegroups.com
> Date: 08/12/2013 11:57AM
> Subject: [CP2K:4549] Bulk modulus of silicon with CP2K
>
> Hi all,
>
> I simulated the silicon with 64 atoms and calculated the energy-volume
> plot and fitted with murnaghan.
> I found the lattice parameter 5.48 A ( lattice parameter in experiment is
> 5.44 A), That is OK but the bulk modulus is 63 GPa that is very low. (B_exp
> = 100 GPa)
> I really don' t know why cp2k gets B so low???
>
> I tried with DZVP basis set and PBE functional with 280 Ryd cut off for
> density.
> I also checked with TZVP, it is not changing so much. It is 66 GPa.
> Can anybody help me with that?
> You can find my inputfile in below.
>
> &GLOBAL
>   PROJECT si64-10.88A
>   PRINT_LEVEL LOW
>   RUN_TYPE GEO_OPT
> &END GLOBAL
> &MOTION
>   &CELL_OPT
>     TYPE GEO_OPT
>     OPTIMIZER CG
>     MAX_ITER 20
>     EXTERNAL_PRESSURE [bar] 1.0
>     MAX_DR 0.02
>     RMS_DR 0.01
>     MAX_FORCE 0.0002
>     RMS_FORCE 0.0001
>     KEEP_ANGLES
>     &CG
>       &LINE_SEARCH
>         TYPE 2PNT
>         &2PNT
>         &END
>       &END
>     &END
>   &END
>   &GEO_OPT
>     MAX_ITER 200
>     MINIMIZER BFGS
>   &END
>   &PRINT
>     &STRESS
>     &END STRESS
>     &RESTART
>       &EACH
>         CELL_OPT 1
>       &END
>     &END
>   &END
> &END
> &FORCE_EVAL
>   METHOD QS
>   STRESS_TENSOR ANALYTICAL
>   &DFT
>     BASIS_SET_FILE_NAME ./BASIS_MOLOPT
>     POTENTIAL_FILE_NAME ./GTH_POTENTIALS
>     &MGRID
>       CUTOFF 280
>     &END MGRID
>     &QS
>       METHOD GPW
>     &END QS
>     &SCF
>       SCF_GUESS RESTART
>       MAX_SCF 20
>       EPS_SCF 1.0e-5
>       &OUTER_SCF
>       EPS_SCF 1.0E-5
>       &END
>       &OT ON
> #        MINIMIZER DIIS
>          ROTATION
>       &END OT
>       &PRINT
>         &RESTART
>           BACKUP_COPIES 0
>         &END RESTART
>       &END PRINT
>     &END SCF
>     &XC
>       &XC_FUNCTIONAL PBE
>       &END XC_FUNCTIONAL
>       &vdW_POTENTIAL
>          DISPERSION_FUNCTIONAL PAIR_POTENTIAL
>          &PAIR_POTENTIAL
>             TYPE DFTD3
>             CALCULATE_C9_TERM .TRUE.
>             REFERENCE_C9_TERM .TRUE.
>             LONG_RANGE_CORRECTION .TRUE.
>             PARAMETER_FILE_NAME ./dftd3.dat
>             REFERENCE_FUNCTIONAL PBE
>             R_CUTOFF 8.
>             EPS_CN 0.01
>          &END PAIR_POTENTIAL
>       &END vdW_POTENTIAL
>     &END XC
>   &END DFT
>   &SUBSYS
>     &TOPOLOGY
>       COORD_FILE_NAME ./GEOMETRY.xyz
>       COORDINATE XYZ
> #      CONNECTIVITY OFF
>     &END TOPOLOGY
>     &KIND Si
>       BASIS_SET DZVP-MOLOPT-SR-GTH
> #      BASIS_SET SZV-MOLOPT-SR-GTH
> #       BASIS_SET TZVP-MOLOPT-GTH
>       POTENTIAL GTH-PBE-q4
>     &END
>     &CELL
>       ABC    10.88  10.88 10.88
>     &END
>   &END SUBSYS
>  &END
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