AMBER Archive (2008)

Subject: AMBER: How to adjust the problem of "Vlimit exceeded"

From: Biman Jana (
Date: Mon Jun 23 2008 - 02:28:27 CDT

Dear Users,
           I am doing a simulation of bulk water of TIP5P model system
using amber7 for several temperatures starting from T = 300K down to T =
230K. For lower temperatures, I am getting error mesages leke,
"vlimit exceeded for step 1458654; vmax = 20.0072408"
This type of messages i am getting for several time for a run. Please let
me know how dangerous it is and also provide me some idea of avoiding the
same. I am pasting the input file for the run below.

   irest = 0, ntx = 1,
   ntb = 2, ntp = 1, taup=0.1,
   cut = 8.0,
   ntf=2, ntc=2, tol=0.000001,
   nstlim=1600000, ntpr=100,
   NTWX=0,NSCM = 1000,NTWR=500,
   ntt=1, temp0=245., tautp=0.1,

Thanking you.

Biman Jana

" My natural philosophical disposition is not to work on big questions. I
like working on many detailed small problems in this wonderful chemical
garden, while keeping my eyes open for the connections."

Roald Hoffmann

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