Unusual Behavior of CELL opt progress of CP2K26

Babu mpb... at gmail.com
Mon Oct 19 07:09:01 CEST 2015


hi, Jianfeng Jia,

Can you please describe how you define
      &CELL
       A     3.9239  0.0000000000000000E+00    0.0000000000000000E+00
       B     0.0000000000000000E+00    3.9239   0.0000000000000000E+00
       C     0.0000000000000000E+00    0.0000000000000000E+00    3.9239     
 these values for your pt atom.

On Sunday, 11 October 2015 12:44:08 UTC+5:30, jjf... at yahoo.com.cn wrote:
>
> Dear All,
>
> I am using CP2K to optimize the cell of Pt metal. The input is as below,
>  &GLOBAL
>    PRINT_LEVEL  LOW
>    PROJECT_NAME Pt
>    RUN_TYPE  CELL_OPT
>  &END GLOBAL
>  &MOTION
>    &CELL_OPT
>      OPTIMIZER  BFGS
>      KEEP_SYMMETRY T
>    &END CELL_OPT
>  &END MOTION
>  &FORCE_EVAL
>    METHOD  QS
>    STRESS_TENSOR  ANALYTICAL
>    &DFT
>      &SCF
>        MAX_SCF  50
>        EPS_SCF     9.9999999999999995E-10
>         CHOLESKY  INVERSE
>         ADDED_MOS 500
>    &MIXING
>    METHOD BROYDEN_MIXING
>    ALPHA   0.1
>    BETA    0.7
>    NBROYDEN  8
>    &END
>    &SMEAR  ON
>      METHOD FERMI_DIRAC
>      ELECTRONIC_TEMPERATURE [K] 100
>    &END SMEAR
>    &DIAGONALIZATION T
>    &END DIAGONALIZATION
>      &END SCF
>      &QS
>        METHOD  GPW
>        EPS_DEFAULT 1.0E-12
>     EXTRAPOLATION USE_GUESS
>      &END QS
>      &MGRID
>        CUTOFF     4.0000000000000000E+02
>      &END MGRID
>      &XC
>        DENSITY_CUTOFF     1.0000000000000000E-10
>        GRADIENT_CUTOFF     1.0000000000000000E-10
>        TAU_CUTOFF     1.0000000000000000E-10
>        &XC_FUNCTIONAL  NO_SHORTCUT
>          &PBE  T
>          &END PBE
>        &END XC_FUNCTIONAL
>        &VDW_POTENTIAL
>          POTENTIAL_TYPE  PAIR_POTENTIAL
>          &PAIR_POTENTIAL
>            R_CUTOFF     9.0000000000000000E+00
>            TYPE  DFTD3
>            PARAMETER_FILE_NAME /lustre/home/jiajf/cp2k/dftd3.dat
>            REFERENCE_FUNCTIONAL PBE
>            EPS_CN     9.9999999999999995E-07
>            CALCULATE_C9_TERM  T
>            REFERENCE_C9_TERM  T
>            LONG_RANGE_CORRECTION  T
>            VERBOSE_OUTPUT  F
>          &END PAIR_POTENTIAL
>        &END VDW_POTENTIAL
>      &END XC
>      &POISSON
>        POISSON_SOLVER  PERIODIC
>        PERIODIC  XYZ
>      &END POISSON
>    &END DFT
>    &SUBSYS
>      &CELL
>        A     3.9239  0.0000000000000000E+00    0.0000000000000000E+00
>        B     0.0000000000000000E+00    3.9239   0.0000000000000000E+00
>        C     0.0000000000000000E+00    0.0000000000000000E+00    3.9239
>        PERIODIC  XYZ
>        SYMMETRY CUBIC
>       MULTIPLE_UNIT_CELL  4 4 4
>      &END CELL
>      &COORD
> Pt  0.0000    0.0000    0.0000
> Pt  0.0000    1.9620    1.9620
> Pt  1.9620    0.0000    1.9620
> Pt  1.9620    1.9620    0.0000
>      &END COORD
>      &KIND Pt
>        BASIS_SET DZVP-MOLOPT-SR-GTH
>        POTENTIAL GTH-PBE-q18
>      &END KIND
>      &TOPOLOGY
>       MULTIPLE_UNIT_CELL  4 4 4
>      &END TOPOLOGY
>    &END SUBSYS
>  &END FORCE_EVAL
>
> It can achieve covegence smoothly after about 8 SCF-cycles. However, I 
> found the energies from each SCF-cycle were below,
> ENERGY| Total FORCE_EVAL ( QS ) energy (a.u.):           
> -30774.690068596093624
> ENERGY| Total FORCE_EVAL ( QS ) energy (a.u.):           
> -30774.474988016871066
> ENERGY| Total FORCE_EVAL ( QS ) energy (a.u.):           
> -30773.785173646669136
> ENERGY| Total FORCE_EVAL ( QS ) energy (a.u.):           
> -30772.813279130394221
> ENERGY| Total FORCE_EVAL ( QS ) energy (a.u.):           
> -30772.382090925824741
> ENERGY| Total FORCE_EVAL ( QS ) energy (a.u.):           
> -30772.370917807555088
> ENERGY| Total FORCE_EVAL ( QS ) energy (a.u.):           
> -30772.370406719932362
> ENERGY| Total FORCE_EVAL ( QS ) energy (a.u.):           
> -30772.370389366384188
>
> It is clearly that the optimzed cell has higher energy than the original 
> cell. It is out of my understanding. Anyone can help?
>
> Jianfeng Jia
>
>
>
>  
>
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