Dear all,<br>             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 ?  <br>
<br>Any suggestions/comments/help is greatly appreciated.    <br><br>Input file :<br><br>&FORCE_EVAL<br>  METHOD Quickstep<br>  STRESS_TENSOR ANALYTICAL<br>  &DFT<br>    BASIS_SET_FILE_NAME /home/others/jncasr/software/cp2k/tests/QS/BASIS_MOLOPT<br>
    POTENTIAL_FILE_NAME /home/others/jncasr/software/cp2k/tests/QS/POTENTIAL<br>    CHARGE = 0  <br>    &MGRID<br>      CUTOFF 1300<br>      NGRIDS 5 <br>      REL_CUTOFF 40<br>    &END MGRID<br>     &QS<br>       METHOD GPW<br>
       EPS_DEFAULT 1.0E-10<br>     &END QS<br>     &SCF<br>       SCF_GUESS ATOMIC  <br>       EPS_SCF 1.0E-8<br>       MAX_SCF 50<br>#       MIXING 0.3<br>       &OUTER_SCF<br>          EPS_SCF 1.0E-8<br>          MAX_SCF 5<br>
       &END<br>    &OT<br>          MINIMIZER CG<br>          PRECONDITIONER FULL_ALL<br>          ENERGY_GAP 0.001<br>          STEPSIZE 0.05<br>       &END<br> <br>    &END SCF<br>    &XC<br>     &XC_FUNCTIONAL BLYP <br>
     &END XC_FUNCTIONAL<br>     &vdW_POTENTIAL<br>      DISPERSION_FUNCTIONAL PAIR_POTENTIAL<br>      &PAIR_POTENTIAL<br>         TYPE DFTD2<br>         REFERENCE_FUNCTIONAL BLYP <br>      &END PAIR_POTENTIAL<br>
     &END vdW_POTENTIAL<br>      &XC_GRID<br>        XC_DERIV  SPLINE2<br>        XC_SMOOTH_RHO NN50<br>     &END XC_GRID<br>   &END XC<br>  &END DFT<br><br>  &SUBSYS<br>    &CELL <br>      ABC 10.9310  16.2099   43.6020  <br>
     ALPHA_BETA_GAMMA  90.0  92.754   90.00 <br>    &END CELL<br><br>    &COORD<br>     @INCLUDE coor.xyz  <br>    &END COORD<br><br>     &KIND H<br>      BASIS_SET DZVP-MOLOPT-SR-GTH<br>      POTENTIAL GTH-BLYP-q1<br>
    &END KIND<br>    <br>     &KIND C<br>      BASIS_SET DZVP-MOLOPT-SR-GTH<br>      POTENTIAL GTH-BLYP-q4<br>    &END KIND<br><br>     &KIND N<br>      BASIS_SET DZVP-MOLOPT-SR-GTH<br>      POTENTIAL GTH-BLYP-q5<br>
    &END KIND<br>    <br>     &KIND Zn<br>      BASIS_SET DZVP-MOLOPT-SR-GTH<br>      POTENTIAL GTH-BLYP-q12<br>    &END KIND<br><br>    &KIND F<br>      BASIS_SET DZVP-MOLOPT-SR-GTH<br>      POTENTIAL GTH-BLYP-q7<br>
    &END KIND<br><br>    &KIND Si <br>      BASIS_SET DZVP-MOLOPT-SR-GTH<br>      POTENTIAL GTH-BLYP-q4<br>    &END KIND<br><br>    &KIND O <br>      BASIS_SET  DZVP-MOLOPT-SR-GTH<br>      POTENTIAL GTH-BLYP-q6<br>
    &END KIND<br><br><br>  &END SUBSYS<br>&END FORCE_EVAL<br><br>&GLOBAL<br>  PROJECT OUT-MOF<br>  RUN_TYPE ENERGY_FORCE  <br>  PRINT_LEVEL MEDIUM<br>&END GLOBAL<br><br><br><br>&EXT_RESTART<br>    RESTART_FILE_NAME  OUT-MOF-1.restart<br>
    RESTART_DEFAULT  F <br>    RESTART_POS   T  <br>&END EXT_RESTART<br><br><br>Thanks. <br><br>Regards,<br>Sandeep<br><br><br><br>