small Jump in Conserved Quantity

Francesco francesc... at gmail.com
Tue Jun 2 16:56:26 CEST 2009


Hi to all,
following a NVE simulation of an isolated molecule, I found that after
the restart there's a jump in the Conserved Quantity ( I obtain jumps
like this each time I restart the simulation).

#  Step Nr.          Time[fs]               Kin.[a.u.]
Temp[K]                Pot.[a.u.]             Cons Qty[a.u.]
      2040         1020.000000         0.060956952
188.712354820      -350.782198702      -350.721241749
      2041         1020.500000         0.060918552
188.593475153      -350.782159564      -350.721241011
      2042         1021.000000         0.060888428
188.500213394      -350.782128677      -350.721240249
      2043         1021.500000         0.060871701
188.448430001      -350.782111378      -350.721239677
      2044         1022.000000         0.060872854
188.452001719      -350.782111983      -350.721239129
      2045         1022.500000         0.060895749
188.522878866      -350.782134430      -350.721238681
      2046         1023.000000         0.060943620
188.671078602      -350.782181953      -350.721238333
      2047         1023.500000         0.061019026
188.904523257      -350.782256965      -350.721237939
      2048         1024.000000         0.061123792
189.228861046      -350.782361468      -350.721237677

 
RESTART

      2041         1020.500000         0.060949314
188.688708063      -350.782442958      -350.721493644
      2042         1021.000000         0.060941947
188.665901432      -350.782435584      -350.721493636
      2043         1021.500000         0.060938872
188.656381373      -350.782432557      -350.721493684
      2044         1022.000000         0.060944036
188.672366867      -350.782437451      -350.721493415
      2045         1022.500000         0.060961411
188.726156528      -350.782454251      -350.721492841
      2046         1023.000000         0.060994791
188.829498101      -350.782486835      -350.721492043
      2047         1023.500000         0.061047420
188.992425479      -350.782538667      -350.721491247
      2048         1024.000000         0.061122123
189.223695729      -350.782613042      -350.721490918

Is this "jump" a round off problem?
Is it small (I mean negligible)?

Attached the input file
----
In the input file I've chosen to print the ener file for each step,
while the position, velocity, wave functions and restart each 20 step
---


&EXT_RESTART
   RESTART_FILE_NAME RX1bis-RX2TS-1.restart
&END EXT_RESTART
&MOTION
  &MD
   COMVEL_TOL 1E-08
   ANGVEL_ZERO T
   ENSEMBLE NVE
   STEPS 3000
   TIMESTEP 0.5
!   TEMPERATURE 300.0
!   &THERMOSTAT
!      TYPE NOSE
!      REGION GLOBAL
!      &NOSE
!        LENGTH 4
!        TIMECON 20
!      &END NOSE
!   &END THERMOSTAT
  &END MD
  &PRINT
    &TRAJECTORY
      &EACH
        MD 20
      &END EACH
    &END TRAJECTORY
    &VELOCITIES
      &EACH
        MD 20
      &END EACH
    &END VELOCITIES
    &RESTART
      &EACH
        MD 20
      &END EACH
    &END RESTART
  &END PRINT
  &GEO_OPT
  &END GEO_OPT
&END MOTION
&FORCE_EVAL
   METHOD QS
   &DFT
      &POISSON
       POISSON_SOLVER WAVELET
       PERIODIC NONE
     &END POISSON
     BASIS_SET_FILE_NAME BASIS_NEW
     POTENTIAL_FILE_NAME POT_NEW
     WFN_RESTART_FILE_NAME RX1bis-RX2TS-RESTART.wfn
     MULTIPLICITY 1
     CHARGE 0
    &MGRID
      CUTOFF 300
    &END MGRID
    &QS
      EXTRAPOLATION ASPC
      EXTRAPOLATION_ORDER 3
    &END QS
    &SCF
      EPS_SCF 1.0E-6
      SCF_GUESS RESTART
      MAX_SCF 500
      &PRINT
        &RESTART
          &EACH
            MD 20
          &END EACH
        &END RESTART
      &END PRINT
      &OT
        MINIMIZER DIIS
        N_DIIS 7
        PRECONDITIONER FULL_SINGLE_INVERSE
      &END OT
      &OUTER_SCF
        EPS_SCF 1.0E-4
        MAX_SCF 4
      &END OUTER_SCF
    &END SCF
    &XC
      &XC_FUNCTIONAL PBE
      &END XC_FUNCTIONAL
    &END XC
  &END DFT
  &SUBSYS
    &TOPOLOGY
       CENTER_COORDINATES T
    &END TOPOLOGY
    &CELL
      ABC 20.0 20.0 20.0
      PERIODIC NONE
    &END CELL
    &COORD
    &END COORD
    &VELOCITY
    &END VELOCITY
    &KIND H
      BASIS_SET DZVP-GTH-PBE
      POTENTIAL GTH-PBE-q1
    &END KIND
    &KIND C
      BASIS_SET DZVP-GTH-PBE
      POTENTIAL GTH-PBE-q4
    &END KIND
    &KIND N
     BASIS_SET DZVP-GTH-PBE
     POTENTIAL GTH-PBE-q5
    &END KIND
    &KIND Cl
     BASIS_SET DZVP-GTH-BLYP
     POTENTIAL GTH-PBE-q7
    &END KIND
  &END SUBSYS
&END FORCE_EVAL
&GLOBAL
  PROJECT_NAME RX1bis-RX2TS
  RUN_TYPE MD
  PRINT_LEVEL MEDIUM
&END GLOBAL


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