Restart NVT

[Lucas Lodeiro]

Hi all,

I am running NVT water box AIMD in CP2K 7.0.

The run stopped this morning due to node problem, but I can restart it using the restart file.

But I see some differences that I can not understand.

I use the same input data to do the restart, but I added:

&EXT_RESTART
  EXTERNAL_FILE              WATER-1.restart
  RESTART_THERMOSTAT         .FALSE.
&END EXT_RESTART

To restart the calculation and to not restart the thermostat. I guess this is the correct way to restart a MD without changing the thermostat behaviour.

But in the first step I see some weird data in *.ener file.

I see in the first new step, the Cons Qty[a.u.] change a little, respect the last step after MD stopped.

Also for the n-last steps after MD stopped, the temperature oscillates just +-10°C around the objective temperature and the average temperature was the correct objective temperature. In the first n-steps of the restart MD, the temperature starts oscillating more than 10 °C (in cases 30°C), but the average temperature was correct respect the last average temperature and objective temperature.

This is a part of the data (step 28945 is the first step of restart MD):

     28925        14462.500000         0.524397237       292.822905020     -2167.386128946     -2166.788489113         9.942549903
     28926        14463.000000         0.523902002       292.546366555     -2167.385787588     -2166.788513509        18.580139473
     28927        14463.500000         0.521503538       291.207066513     -2167.383420424     -2166.788416738        15.250579394
     28928        14464.000000         0.518609792       289.591201566     -2167.380528831     -2166.788292618        17.792272486
     28929        14464.500000         0.517109605       288.753498602     -2167.379085941     -2166.788225441        10.424001478
     28930        14465.000000         0.518164941       289.342797441     -2167.380271236     -2166.788232301         9.924992632
     28931        14465.500000         0.521824007       291.386016117     -2167.384120605     -2166.788300216        15.055006087
     28932        14466.000000         0.527128166       294.347853254     -2167.389667610     -2166.788420716        10.627952956
     28933        14466.500000         0.532342877       297.259742512     -2167.395139856     -2166.788555528        14.917385891
     28934        14467.000000         0.535600841       299.078986930     -2167.398592480     -2166.788627084        10.879262459
     28935        14467.500000         0.535936944       299.266666470     -2167.399018273     -2166.788593698        10.006427173
     28936        14468.000000         0.533834852       298.092860267     -2167.396936550     -2166.788491610         9.977815259
     28937        14468.500000         0.530754526       296.372809252     -2167.393877604     -2166.788391632        10.085333489
     28938        14469.000000         0.528128677       294.906537823     -2167.391326816     -2166.788346629        10.028149899
     28939        14469.500000         0.526585940       294.045074707     -2167.389919732     -2166.788363449         9.960049219
     28940        14470.000000         0.525859267       293.639301105     -2167.389345953     -2166.788398597        14.496977419
     28941        14470.500000         0.525379287       293.371280876     -2167.388985539     -2166.788401415        14.967396073
     28942        14471.000000         0.524959273       293.136745417     -2167.388649341     -2166.788369463        10.315914560
     28943        14471.500000         0.524874770       293.089558993     -2167.388653910     -2166.788343715        16.983571853
     28944        14472.000000         0.525392050       293.378407716     -2167.389290137     -2166.788348686        12.119731613
     28945        14472.500000         0.526406871       293.945083066     -2167.390481370     -2166.863446252        47.022801183
     28946        14473.000000         0.527734481       294.686419018     -2167.391978869     -2166.863459996        11.051850852
     28947        14473.500000         0.529255279       295.535631285     -2167.393652283     -2166.863456336        10.006576888
     28948        14474.000000         0.531086126       296.557974111     -2167.395616229     -2166.863432883         9.709443437
     28949        14474.500000         0.533577404       297.949101425     -2167.398244277     -2166.863412585         9.787318693
     28950        14475.000000         0.537016875       299.869698620     -2167.401858321     -2166.863429212         9.785394795
     28951        14475.500000         0.541258217       302.238060033     -2167.406305123     -2166.863475419         9.731476160
     28952        14476.000000         0.545774333       304.759854865     -2167.411027429     -2166.863520675         9.752394203
     28953        14476.500000         0.549990896       307.114379332     -2167.415448002     -2166.863561837         9.763660893
     28954        14477.000000         0.553359699       308.995515632     -2167.419028509     -2166.863608727         9.769082915
     28955        14477.500000         0.555299389       310.078636660     -2167.421167132     -2166.863641041         9.809159193
     28956        14478.000000         0.555434584       310.154129550     -2167.421461446     -2166.863632113         9.759279175
     28957        14478.500000         0.553874622       309.283048227     -2167.420037090     -2166.863598770         9.749239432
     28958        14479.000000         0.551014039       307.685701343     -2167.417323889     -2166.863576839         9.767714364
     28959        14479.500000         0.547123637       305.513304502     -2167.413592074     -2166.863566261         9.815094918
     28960        14480.000000         0.542330631       302.836894640     -2167.408945453     -2166.863544138         9.748038203
     28961        14480.500000         0.536899528       299.804172240     -2167.403638144     -2166.863500571        10.112055471
     28962        14481.000000         0.531402812       296.734811186     -2167.398244733     -2166.863438049         9.841474611
     28963        14481.500000         0.526676227       294.095490925     -2167.393620245     -2166.863376014         9.819765911
     28964        14482.000000         0.523490986       292.316855534     -2167.390580350     -2166.863358790         9.816407133
     28965        14482.500000         0.521971605       291.468434880     -2167.389273875     -2166.863410344         9.819614979
     28966        14483.000000         0.521357575       291.125560959     -2167.388891848     -2166.863481893         9.822640346

Why is happening this step shift in the conserved quantity, and the change in the temperature MD behaviour? Is this normal for a restart MD?

Regards

[Thomas Kühne]

Dear Lucas 

simply set RESTART_THERMOSTAT TRUE (or remove the line since this is the default) 

to restart the state of the thermostat. The behavior you observe is an artifact due to restarting 

positions and velocities but resetting the thermostat … 

Cheers, 

Thomas

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==============================

Thomas D. Kühne

Dynamics of Condensed Matter

Chair of Theoretical Chemistry

University of Paderborn

Warburger Str. 100

D-33098 Paderborn

Germany

tdku...@mail.upb.de

+49/(0)5251/60-5726

[Lucas Lodeiro]

Thanks Thomas, I was a little confused between restart and resetting, now its clear for me :).

Regards!

To view this discussion on the web visit https://groups.google.com/d/msgid/cp2k/F52D1EB6-2425-4A82-8167-AF7DB79B7790%40gmail.com.