The center of masses drift problem

[mat1... at gmail.com]

Hello,

I'm performing ab initio MD run to calculate further the IR spectrum.
I've done a non-periodic NVE test simulation of a molecule of water
(the input below), but I found that there is a drift of the center of
masses. Is there any way to avoid it?


Regards,




&FORCE_EVAL
  METHOD Quickstep
 &DFT
      BASIS_SET_FILE_NAME GTH_BASIS_SETS
      POTENTIAL_FILE_NAME POTENTIAL
     &MGRID
      CUTOFF 300
     &END MGRID
     &QS
     &END QS
     &SCF
      SCF_GUESS ATOMIC
     &END SCF
      &XC
      &XC_FUNCTIONAL BLYP
      &END XC_FUNCTIONAL
    &END XC
    &POISSON
        PERIODIC NONE
        POISSON_SOLVER MULTIPOLE
       &MULTIPOLE
          EWALD_PRECISION 0.00000001
          RCUT 4.0
          ANALYTICAL_GTERM
       &END MULTIPOLE
    &END POISSON
    &PRINT
      &LOCALIZATION
          EACH 1
          LOC_TYPE CRAZY
          MOLECULAR_DIPOLES T
          TOTAL_DIPOLE T
      &END LOCALIZATION
    &END PRINT
 &END DFT
 &SUBSYS
     &CELL
        ABC 8.0 8.0 8.0
        UNIT ANGSTROM
        PERIODIC NONE
     &END CELL
     &COORD
        O        -1.3459376534       -0.0354156443        0.1465219667
        H        -1.6005239833        0.7471984224       -0.3684408375
        H        -1.6119945737       -0.7853664624       -0.4092127268
     &END COORD
     &KIND O
        BASIS_SET DZVP-GTH
        POTENTIAL GTH-BLYP-q6
     &END KIND
     &KIND H
        BASIS_SET DZVP-GTH
        POTENTIAL GTH-BLYP-q1
     &END KIND
  &END SUBSYS
&END FORCE_EVAL
&GLOBAL
   FFTLIB FFTSG
   PROJECT water
   RUN_TYPE MD
   PRINT_LEVEL LOW
&END GLOBAL
&MOTION
  &MD
    ENSEMBLE NVE
    STEPS 10000
    TIMESTEP 0.2
    TEMPERATURE 300
 &END MD
  &PRINT
    &RESTART
      EACH 1
    &END
    &RESTART_HISTORY OFF
    &END
    &TRAJECTORY
      EACH 1
    &END
    &VELOCITIES
      EACH 1
    &END
   &END
&END