Re: error : atom moving too fast

From: muniyamuthu.raviprasad_at_ndsu.edu
Date: Wed May 05 2010 - 09:58:50 CDT

Hi

According to your configuration file, your langevinTemp (290) is too high.
It applies large force in the system and it moves atom very fast.

try these

1] Apply the temperature step by step (100 200 290 ..)
2] You can use smaller time step (1 fs or 0.5 fs)
3] make sure all atoms inside the cell basis vector
4] use Velocity control or Temperature control with Langivin Dynamics

I hope it will work

Ravi

> Hi all,
> I have been getting an error during the heating after 50000
> steps of minimization. The error is like this :
>
> ENERGY: 50080 6900.3852 6903.3658 3540.2068
> 50.1815 -133358.2452 13139.9822 18.9646 0.0000
> 12009.7203 -90795.4389 104.3929 -89735.2082
> -89012.8941 102.7365 3460.7576 1431.2232
> 516713.1384 1440.3727 1949.4518
>
> ERROR: Atom 568 velocity is 24014.9 41973.4 26943.1 (limit is 5000)
ERROR: Atom 574 velocity is -23402.1 -44094 -37182.6 (limit is 5000)
ERROR: Atom 576 velocity is -461.405 -5353.41 1739.84 (limit is 5000)
ERROR: Atoms moving too fast; simulation has become unstable.
> ERROR: Exiting prematurely.
>
> I have peptide-bilayer system, and I check the pbc condition which is
allright.
> I would like to know if anyone knows how to solve this problem as I
> really need it. I am attaching herewith the input file.
>
> --
> Ipsita Basu
> Research Fellow
> c/o : Dr. Chaitali Mukhopadhyay
> Rajabazar Science College
> 92 APC Road
> Kolkata - 700009
>

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