density cutoff value for stress convergence

[Sandeep Kumar Reddy]

Dear all,
             I want to do cell optimization of a system containing 560
atoms. Before that, to know the proper value of density cutoff, i have
carried out series of single point calculations  to calculate STRESS tensor
at different values of density cutoffs. Trace of this tensor are plotted
against density cutoff,  shown in enclosed Fig... It shows trace of the
tensor seems to be converging at 600 Ry.  Is it ok to take this value for
this calculation ?

Any suggestions/comments/help is greatly appreciated.

Input file :

&FORCE_EVAL
  METHOD Quickstep
  STRESS_TENSOR ANALYTICAL
  &DFT
    BASIS_SET_FILE_NAME
/home/others/jncasr/software/cp2k/tests/QS/BASIS_MOLOPT
    POTENTIAL_FILE_NAME /home/others/jncasr/software/cp2k/tests/QS/POTENTIAL
    CHARGE = 0
    &MGRID
      CUTOFF 1300
      NGRIDS 5
      REL_CUTOFF 40
    &END MGRID
     &QS
       METHOD GPW
       EPS_DEFAULT 1.0E-10
     &END QS
     &SCF
       SCF_GUESS ATOMIC
       EPS_SCF 1.0E-8
       MAX_SCF 50
#       MIXING 0.3
       &OUTER_SCF
          EPS_SCF 1.0E-8
          MAX_SCF 5
       &END
    &OT
          MINIMIZER CG
          PRECONDITIONER FULL_ALL
          ENERGY_GAP 0.001
          STEPSIZE 0.05
       &END

    &END SCF
    &XC
     &XC_FUNCTIONAL BLYP
     &END XC_FUNCTIONAL
     &vdW_POTENTIAL
      DISPERSION_FUNCTIONAL PAIR_POTENTIAL
      &PAIR_POTENTIAL
         TYPE DFTD2
         REFERENCE_FUNCTIONAL BLYP
      &END PAIR_POTENTIAL
     &END vdW_POTENTIAL
      &XC_GRID
        XC_DERIV  SPLINE2
        XC_SMOOTH_RHO NN50
     &END XC_GRID
   &END XC
  &END DFT

  &SUBSYS
    &CELL
      ABC 10.9310  16.2099   43.6020
     ALPHA_BETA_GAMMA  90.0  92.754   90.00
    &END CELL

    &COORD
     @INCLUDE coor.xyz
    &END COORD

     &KIND H
      BASIS_SET DZVP-MOLOPT-SR-GTH
      POTENTIAL GTH-BLYP-q1
    &END KIND

     &KIND C
      BASIS_SET DZVP-MOLOPT-SR-GTH
      POTENTIAL GTH-BLYP-q4
    &END KIND

     &KIND N
      BASIS_SET DZVP-MOLOPT-SR-GTH
      POTENTIAL GTH-BLYP-q5
    &END KIND

     &KIND Zn
      BASIS_SET DZVP-MOLOPT-SR-GTH
      POTENTIAL GTH-BLYP-q12
    &END KIND

    &KIND F
      BASIS_SET DZVP-MOLOPT-SR-GTH
      POTENTIAL GTH-BLYP-q7
    &END KIND

    &KIND Si
      BASIS_SET DZVP-MOLOPT-SR-GTH
      POTENTIAL GTH-BLYP-q4
    &END KIND

    &KIND O
      BASIS_SET  DZVP-MOLOPT-SR-GTH
      POTENTIAL GTH-BLYP-q6
    &END KIND


  &END SUBSYS
&END FORCE_EVAL

&GLOBAL
  PROJECT OUT-MOF
  RUN_TYPE ENERGY_FORCE
  PRINT_LEVEL MEDIUM
&END GLOBAL



&EXT_RESTART
    RESTART_FILE_NAME  OUT-MOF-1.restart
    RESTART_DEFAULT  F
    RESTART_POS   T
&END EXT_RESTART


Thanks.

Regards,
Sandeep
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