Lowdin analysis

Manh manht... at gmail.com
Fri Dec 3 17:46:51 CET 2010


Hello everyone,

I calculate the Mulliken and Lowdin charges for a water molecule. The
results are:

----------------------------------------------------------------

 MULLIKEN POPULATION ANALYSIS

 # Atom  Element  Kind  Atomic population                Net charge
      1     H        1           0.780838                  0.219162
      2     H        1           0.780981                  0.219019
      3     O        2           6.438182                 -0.438182
 # Total charge                  8.000000                  0.000000



 LOWDIN POPULATION ANALYSIS

 # Atom  Element  Kind  Atomic population                Net charge
      1     H        1           1.210449                 -0.210449
      2     H        1           1.210473                 -0.210473
      3     O        2           5.579079                  0.420921
 # Total charge                  8.000000                  0.000000


--------------------------------------------------------

I think that the Lowdin analysis has some problem.

Here is my input:

---------------------------------------------

&FORCE_EVAL
  METHOD Quickstep
  &DFT
    BASIS_SET_FILE_NAME ../../../BASIS_MOLOPT
    POTENTIAL_FILE_NAME ../../../GTH_POTENTIALS
    RESTART_FILE_NAME H2O-RESTART.wfn.wfn
    &QS
      METHOD GPW
      EXTRAPOLATION ASPC
      EXTRAPOLATION_ORDER 3
    &END QS
    &MGRID
      CUTOFF 400
      NGRIDS 5
    &END
    &SCF
      MAX_SCF 20
      SCF_GUESS RESTART
      EPS_SCF 1.0E-6
      &OT
        PRECONDITIONER  FULL_SINGLE_INVERSE
        MINIMIZER  CG
      &END
      &OUTER_SCF
        MAX_SCF 10
        EPS_SCF 1.0E-6
      &END
      &PRINT
        &RESTART
          &EACH
            QS_SCF 0
            GEO_OPT 2
          &END
          ADD_LAST NUMERIC
          FILENAME RESTART.wfn
        &END
        &RESTART_HISTORY OFF
        &END
      &END
    &END SCF

    &XC
      &XC_FUNCTIONAL PBE
      &END XC_FUNCTIONAL
    &END XC

    &PRINT
     &MULLIKEN
     &END MULLIKEN

     &LOWDIN
     &END LOWDIN
    &END

  &END DFT
  &SUBSYS
    &CELL
   ABC [angstrom]   30 30 30
    &END CELL
    &TOPOLOGY
      COORD_FILE_NAME water.xyz
      COORDINATE xyz
    &END

    &KIND O
      BASIS_SET TZV2P-MOLOPT-GTH
      POTENTIAL GTH-PBE-q6
    &END KIND
    &KIND H
      BASIS_SET TZV2P-MOLOPT-GTH
      POTENTIAL GTH-PBE-q1
    &END KIND

  &END SUBSYS

&END FORCE_EVAL

&GLOBAL
  PRINT_LEVEL LOW
  PROJECT H2O
  RUN_TYPE ENERGY
  WALLTIME 285000
&END GLOBAL

&MOTION
    &GEO_OPT
     MAX_ITER 5000
     MAX_FORCE 0.00010
     OPTIMIZER BFGS
    &BFGS
    &END
  &END
&END

------------------------------------------------
 the water.xyz file is
----------------------------------------
       3
 water
  H         8.4351137971        5.1620318678       12.1510352783
  H         8.5534822942        3.6347695084       12.1803075532
  O         7.9011326518        4.3528437024       12.1874564118
------------------------------------------------

Regards,
Manh



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