Re: Problem with number of steps > 1000000

From: Peter Freddolino (petefred_at_ks.uiuc.edu)
Date: Mon Jan 05 2009 - 08:11:57 CST

Is this your first run or are you restarting from a previous run? NAMD
should be able to do runs significantly longer than 1000000 steps, but
if you are restarting from a previous run using firsttimestep, if you
ever go above 2^31 steps you can overflow the integer used to store the
step number. The only good solution currently is to restart your
timestep numbering from 0 (firsttimestep 0), and offset all the step
numbers of subsequent runs by an appropriate amount during postprocessing.
Best,
Peter

Anirban Ghosh wrote:
> Hi ALL,
>
> I am running a implicit solvent CG simulation using NAMD. I am using step
> size as 12 fs. If I try to increase the number of steps beyond 1,000,000
> then I am getting the following error:
>
> ----------------------------------------------------------
> TCL: Running for 10000000 steps
> WRITING EXTENDED SYSTEM TO OUTPUT FILE AT STEP -2101347296
> WRITING COORDINATES TO OUTPUT FILE AT STEP -2101347296
> COORDINATE DCD FILE WAS NOT CREATED
> WRITING VELOCITIES TO OUTPUT FILE AT STEP -2101347296
> ==========================================
> WallClock: 1.766848 CPUTime: 1.239812 Memory: 8180 kB
> ----------------------------------------------------------
>
> Why is this happening? Does NAMD not allow to run simulations with more
> than 1000000 steps? Any suggestion is greatly appreciated.
>
>
> Regards,
>
>
>

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