cell_opt of anatase

motta... at hotmail.com motta... at hotmail.com
Thu Dec 1 15:34:33 CET 2011


Hi
I am a newby of this group.
My probles is the follow: I am trying to perform a cell optimization
of an TiO2 anatase structure, but somewhat does not work. In fact
after tree or four cell cycles the cell expands to much and the
geometry optimization lead to an unrealistic structure too far from
the anatase experimental structure and sine this trend I decide to
stop the run. I started with a 2x2x2 unit cell of anatase (96 atoms)
as the following input declares:

#&EXT_RESTART
#  RESTART_FILE_NAME ./tio2_anatase2x2-GEO_OPT-2-1.restart
#  RESTART_COUNTERS F
#  RESTART_POS T
#  RESTART_VEL F
#  RESTART_THERMOSTAT T
#  RESTART_CONSTRAINT F
#  RESTART_CELL F
#  RESTART_BAROSTAT F
#&END EXT_RESTART
&GLOBAL
  PROJECT tio2_2x2x2
  RUN_TYPE CELL_OPT
  PRINT_LEVEL LOW
&END GLOBAL
&FORCE_EVAL
  METHOD QS
  &DFT
    BASIS_SET_FILE_NAME ../BASIS_MOLOPT
    POTENTIAL_FILE_NAME ../GTH_POTENTIALS
    CHARGE 0
    &MGRID
      CUTOFF 400
      NGRIDS 5
    &END MGRID
    &QS
      METHOD GPW
    &END QS
#    WFN_RESTART_FILE_NAME ./tio2_anatase2x2-GEO_OPT-2-RESTART.wfn
    &SCF
      MAX_SCF 40
      EPS_SCF 1.0E-6
      CHOLESKY OFF
      SCF_GUESS ATOMIC
      &OT
        MINIMIZER CG
        PRECONDITIONER FULL_SINGLE_INVERSE
      &END OT
      &OUTER_SCF
        EPS_SCF 1.0E-6
        MAX_SCF 10
      &END OUTER_SCF
      &PRINT
        &RESTART
        &END
        &RESTART_HISTORY
        &END
      &END PRINT
    &END SCF
    &XC
      &XC_FUNCTIONAL PBE
      &END XC_FUNCTIONAL
      &VDW_POTENTIAL
         POTENTIAL_TYPE PAIR_POTENTIAL
         &PAIR_POTENTIAL
            REFERENCE_FUNCTIONAL PBE
            PARAMETER_FILE_NAME ../dftd3.dat
            TYPE DFTD3
            R_CUTOFF [angstrom] 30
         &END PAIR_POTENTIAL
      &END VDW_POTENTIAL
    &END XC
  &END DFT
 &SUBSYS
    &CELL
      ABC 7.552 7.552 11.328 18.972
      ALPHA_BETA_GAMMA 90.0 90.0 90.0
      PERIODIC XYZ
    &END CELL
    &TOPOLOGY
      COORDINATE XYZ
      COORD_FILE_NAME ./tio2_2x2x2_ini.xyz
      CONNECTIVITY OFF
    &END TOPOLOGY
    &KIND O
      BASIS_SET TZVP-MOLOPT-GTH-q6
      POTENTIAL GTH-PBE-q6
    &END KIND
    &KIND Ti
      BASIS_SET DZVP-MOLOPT-SR-GTH-q12
      POTENTIAL GTH-PBE-q12
    &END KIND
  &END SUBSYS
  STRESS_TENSOR ANALYTICAL
&END FORCE_EVAL
&MOTION
  &CELL_OPT
    TYPE GEO_OPT
    OPTIMIZER CG
    MAX_ITER 1000
    KEEP_ANGLES T
    &CG
      &LINE_SEARCH
        TYPE 2PNT
      &END LINE_SEARCH
    &END CG
  &END CELL_OPT
  &GEO_OPT
    TYPE minimization
    OPTIMIZER BFGS
    MAX_ITER 1000
  &END GEO_OPT
  &PRINT
   &TRAJECTORY
     &EACH
       CELL_OPT 1
     &END EACH
   &END TRAJECTORY
   &STRESS
   &END STRESS
  &END PRINT
&END MOTION

the starting geometry was taken from litterature
Ti       0.000000000      0.000000000      0.000000000
Ti       1.888000000      1.888000000      4.743000000
Ti       0.000000000      1.888000000      2.372000000
Ti       1.888000000      0.000000000      7.114000000
O        0.000000000      0.000000000      1.973000000
O        1.888000000      1.888000000      6.716000000
O        0.000000000      1.888000000      4.345000000
O        1.888000000      0.000000000      9.088000000
O        1.888000000      0.000000000      5.141000000
O        0.000000000      1.888000000      0.398000000
O        1.888000000      1.888000000      2.770000000
O        0.000000000      0.000000000      7.513000000
Ti       3.776000000      0.000000000      0.000000000
Ti       5.664000000      1.888000000      4.743000000
Ti       3.776000000      1.888000000      2.372000000
Ti       5.664000000      0.000000000      7.114000000
O        3.776000000      0.000000000      1.973000000
O        5.664000000      1.888000000      6.716000000
O        3.776000000      1.888000000      4.345000000
O        5.664000000      0.000000000      9.088000000
O        5.664000000      0.000000000      5.141000000
O        3.776000000      1.888000000      0.398000000
O        5.664000000      1.888000000      2.770000000
O        3.776000000      0.000000000      7.513000000
Ti       0.000000000      3.776000000      0.000000000
Ti       1.888000000      5.664000000      4.743000000
Ti       0.000000000      5.664000000      2.372000000
Ti       1.888000000      3.776000000      7.114000000
O        0.000000000      3.776000000      1.973000000
O        1.888000000      5.664000000      6.716000000
O        0.000000000      5.664000000      4.345000000
O        1.888000000      3.776000000      9.088000000
O        1.888000000      3.776000000      5.141000000
O        0.000000000      5.664000000      0.398000000
O        1.888000000      5.664000000      2.770000000
O        0.000000000      3.776000000      7.513000000
Ti       3.776000000      3.776000000      0.000000000
Ti       5.664000000      5.664000000      4.743000000
Ti       3.776000000      5.664000000      2.372000000
Ti       5.664000000      3.776000000      7.114000000
O        3.776000000      3.776000000      1.973000000
O        5.664000000      5.664000000      6.716000000
O        3.776000000      5.664000000      4.345000000
O        5.664000000      3.776000000      9.088000000
O        5.664000000      3.776000000      5.141000000
O        3.776000000      5.664000000      0.398000000
O        5.664000000      5.664000000      2.770000000
O        3.776000000      3.776000000      7.513000000
Ti       0.000000000      0.000000000      9.486000000
Ti       1.888000000      1.888000000     14.229000000
Ti       0.000000000      1.888000000     11.858000000
Ti       1.888000000      0.000000000     16.601000000
O        0.000000000      0.000000000     11.459000000
O        1.888000000      1.888000000     16.202000000
O        0.000000000      1.888000000     13.831000000
O        1.888000000      0.000000000     18.574000000
O        1.888000000      0.000000000     14.627000000
O        0.000000000      1.888000000      9.884000000
O        1.888000000      1.888000000     12.256000000
O        0.000000000      0.000000000     16.999000000
Ti       3.776000000      0.000000000      9.486000000
Ti       5.664000000      1.888000000     14.229000000
Ti       3.776000000      1.888000000     11.858000000
Ti       5.664000000      0.000000000     16.601000000
O        3.776000000      0.000000000     11.459000000
O        5.664000000      1.888000000     16.202000000
O        3.776000000      1.888000000     13.831000000
O        5.664000000      0.000000000     18.574000000
O        5.664000000      0.000000000     14.627000000
O        3.776000000      1.888000000      9.884000000
O        5.664000000      1.888000000     12.256000000
O        3.776000000      0.000000000     16.999000000
Ti       0.000000000      3.776000000      9.486000000
Ti       1.888000000      5.664000000     14.229000000
Ti       0.000000000      5.664000000     11.858000000
Ti       1.888000000      3.776000000     16.601000000
O        0.000000000      3.776000000     11.459000000
O        1.888000000      5.664000000     16.202000000
O        0.000000000      5.664000000     13.831000000
O        1.888000000      3.776000000     18.574000000
O        1.888000000      3.776000000     14.627000000
O        0.000000000      5.664000000      9.884000000
O        1.888000000      5.664000000     12.256000000
O        0.000000000      3.776000000     16.999000000
Ti       3.776000000      3.776000000      9.486000000
Ti       5.664000000      5.664000000     14.229000000
Ti       3.776000000      5.664000000     11.858000000
Ti       5.664000000      3.776000000     16.601000000
O        3.776000000      3.776000000     11.459000000
O        5.664000000      5.664000000     16.202000000
O        3.776000000      5.664000000     13.831000000
O        5.664000000      3.776000000     18.574000000
O        5.664000000      3.776000000     14.627000000
O        3.776000000      5.664000000      9.884000000
O        5.664000000      5.664000000     12.256000000
O        3.776000000      3.776000000     16.999000000

thanks in advace
Alessandro



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