AMBER Archive (2003)

Subject: vlimit exceeded

From: Peter Anderson (toutvabien78_at_yahoo.com)
Date: Sat Jul 05 2003 - 11:39:01 CDT

Dear Amber Users,

I have been running a MD simulation and have had no
problem for the first ~800 ps. However, I just
checked the status of my job and it had quit. The
bottom of the output file has the following message:

vlimit exceeded for step 19679; vmax =1.31771616E+260
vlimit exceeded for step 19681; vmax =215.398889

Coordinate resetting (SHAKE) cannot be accomplished,
deviation is too large
NITER, NIT, LL, I and J are : 0 3 10 5 6

     Note: This is usually a symptom of some deeper
     problem with the energetics of the system.

Here is my input file:

nmropt = 0, irest = 1,
  ntx = 7, ntrx = 1, ntxo = 1,
  ntpr = 100, ntwx = 500, ntwv = 0,
              ntwe = 0,
    ntwr = 5000,
  ntf = 2, ntb = 2,
  cut = 11.0, nsnb = 10,

  nstlim = 250000,
  t = 0.0, dt = 0.002,

  temp0 = 300.0, tempi = 100.0,
  ig = 71277, heat = 0.0,
  ntt = 1,
  tautp = 0.2,
  vlimit = 20.0,

  ntp = 1, pres0 = 1.0, comp = 44.6,
  taup = 0.2, npscal = 1,

  ntc = 2, tol = 0.0005,

 &end

Can someone please tell me whether and how this
problem can be fixed?

Thank you very much,
Peter Anderson

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