job termination

From: ipsita basu (
Date: Fri Feb 11 2011 - 00:46:17 CST

Hi all,
         I have a problem running namd.
         I minimized my system for 200000 steps, I equilibrate the
system using timestep 1fs/step and the job is running without giving
any problem. But during production run when I use 2fs timestep, the
job is terminated frequently after 20 or 30 ps fiving error :
ERROR: Constraint failure in RATTLE algorithm for atom 38767!
ERROR: Constraint failure; simulation has become unstable.
ERROR: Exiting prematurely; see error messages above.
I check the system in vmd, everything is ok. If I again restart the
from that point agin it starts running and is terminated after few ps.
I observe a test run using timestep 1fs, no such problem occures.
My input is attached herewith.
Can anyone please help me.
Thank you.

Ipsita Basu
Research Fellow
c/o : Dr. Chaitali Mukhopadhyay
Rajabazar Science College
92 APC Road
Kolkata - 700009

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