Re: Small discrepancy in Kinetic Energy after restarting the simulation

From: Roman Petrenko (rpetrenko_at_gmail.com)
Date: Tue Dec 01 2009 - 10:55:40 CST

if you didn't use .vel file in restart, the velocities are reassigned
randomly to correspond to given temperature. if the velocities are
different, the kinetic energy must be different.

On Tue, Dec 1, 2009 at 4:10 AM, Mert Gür <gurmert_at_gmail.com> wrote:
> Hi everyone,
> After restarting my simulation I observe that the potential energy is
> exactly the same whereas the kinetic energy differs slightly(Shown below).
> Where does this very small discrepancy in kinetic energy comes from? I was
> considering an roundoff error ....but shouldn't be the same round off error
> included in the potential energy then?
> Thanks in advance.
> Best,
> Mert
>
>
> The last step in my simulation
>
>
> ETITLE:      TS           BOND          ANGLE          DIHED
> IMPRP               ELECT            VDW       BOUNDARY
> MISC        KINETIC               TOTAL           TEMP
> TOTAL2         TOTAL3        TEMPAVG            PRESSURE
> GPRESSURE         VOLUME       PRESSAVG      GPRESSAVG
>
> ENERGY: 5260000      5413.9691      3062.2414        29.5792
> 4.9097         -70309.6491      7182.5188         0.0000         0.0000
> 14544.1653         -40072.2656       309.9742    -39935.0731
> -39936.8342       310.4262           -189.8211      -212.8311
> 153601.2160        11.0813        11.4240
>
> WRITING EXTENDED SYSTEM TO RESTART FILE AT STEP 5260000
> WRITING COORDINATES TO DCD FILE AT STEP 5260000
> WRITING COORDINATES TO RESTART FILE AT STEP 5260000
> FINISHED WRITING RESTART COORDINATES
> WRITING VELOCITIES TO RESTART FILE AT STEP 5260000
> FINISHED WRITING RESTART VELOCITIES
>
>
>
> After restarting my simulation
>
> ETITLE:      TS           BOND          ANGLE          DIHED
> IMPRP               ELECT            VDW       BOUNDARY
> MISC        KINETIC               TOTAL           TEMP
> TOTAL2         TOTAL3        TEMPAVG            PRESSURE
> GPRESSURE         VOLUME       PRESSAVG      GPRESSAVG
>
> ENERGY:       0      5413.9691      3062.2414        29.5792
> 4.9097         -70309.5199      7182.3953         0.0000         0.0000
> 14543.9888         -40072.4364       309.9705    -39935.7659
> -39935.7659       309.9705           -190.6196      -212.3171
> 153601.4592      -190.6196      -212.3171
>
>
>

-- 
Roman Petrenko
Physics Department
University of Cincinnati

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