AMBER Archive (2005)

Subject: AMBER: a problem encountered when trying to equalibrate alanine dipeptide in explicit water

From: Li Su (suli_at_msu.edu)
Date: Wed Aug 24 2005 - 12:36:06 CDT


Dear Amber User,

I encountered a problem when tried to equalibrate alanine dipeptide in
explicit water. After equalibrating ala2 in water with a small restraint on
ala2 with constant volume, I started to equalibrae it with constant
pressure. But it always stopped after several steps of equalibration, show
ing an error message at the bottom of the amber output file like following,

vlimit exceeded for step 1390 ; vmax = 431.631598201490

    Coordinate resetting (SHAKE) was not accomplished
    within 3000 iterations

I thought it might be the problem of not well enough equalibrated in the
constant volume stage. So I tried to elong the time used for the stage from
20ps to 100 ps, but it seemed not to help. If you have any idea about this
problem, could you please tell me. Thank you in advance.

 

Bese Wishes,
Li

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