[CP2K:2102] small Jump in Conserved Quantity

[Teodoro Laino]

Hi,

When you restart you still have the keyword CENTER_COORDINATES in the 
topology section of your input file.
Therefore your system will be centered and since codes in PW (QS is 
partially one of them) are not translational invariant you will get 
slightly different energies (if you move the system around the box).. 
the situation may even be more severe since you use the wavelet decoupling.
The jump will be smaller if you use a larger cutoff., with tuckerman 
decoupling for example, while with wavelet you may still experience 
large jumps.
Two option for you:
1) live with this jump (is anyway small)
2) disable the center_coordinates in the topology section

Teo

Francesco wrote:
> 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
> >
>