Decreasing PE during MD

From: Peter Gannett <pgannett_at_hsc.wvu.edu>
Date: Wed 26 Apr 2000 10:25:00 -0400

Dear Amber Users:

We have been doing long dynamics runs (2-3 ns) under constant pressure . During these runs everything looks pretty good for the first 1ns (temp, pressure, energy all settle down). After the first 1ns, the potential energy begins to fall at an increasing rate so that after 2ns it has dropped off about 10%. And, if you look closely at this term over 0-1ns you can see a slight downward slope. Nothing else appears to be changing (temp, pressure, volume, or kinetic energy. Can anyone tell me what is going on? In case it helps, the mdin file is given below.

Thanks,
Pete Gannett

cgcgcgcgcg, no_mod, warm it up
 &cntrl

  timlim = 999999., nmropt = 0,
  ntx = 5, irest = 1, ntrx = 1, ntxo = 1,
  ntpr = 100, ntwx = 500, ntwv = 0, ntwe = 0,
  ntwxm = 999999, ntwvm = 999999, ntwem = 999999, ioutfm = 0,
  ntwprt = 0,

  ntf = 2, ntb = 2, idiel = 1, dielc = 1.0,
  cut = 9.0, ntnb = 1, nsnb = 10, ntid = 0,
  scnb = 2.0, scee = 1.2, cut2nd = 0.0, ichdna = 0,

  isftrp = 0, rwell = 0.0,

  ipol = 0,

  ibelly = 0, ntr = 0,

  imin = 0,
  maxcyc = 500,
  ncyc = 5000,
  ntmin = 1, dx0 = 0.1, dxm = 0.5, drms = 0.0001,

  nrun = 1,
  nstlim = 999999,
  ndfmin = 0, ntcm = 0, nscm = 0,
  init = 4, t = 0.0, dt = 0.002,

  temp0 = 300.0, tempi = 300.0,
  ig = 71277, heat = 0.0,
  ntt = 1, isolvp = 0, dtemp = 0.0,
  tautp = 0.2, tauts = 0.2,
  vlimit = 20.0,

  tauv0 = 0.0, tauv = 0.1, vzero = 0.0,

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

  ntc = 2, tol = 0.0005,

  imgslt = 0, iftres = 1,
  jfastw = 0,

  ivcap = 0, matcap = 0, fcap = 1.5,

  iewald = 1,
 
 &end
41.4350211 42.3599929 56.9597185 90.0000000 90.0000000 90.0000000
45 45 60 4 0 0 0
0.00001
END
END
Received on Wed Apr 26 2000 - 07:25:00 PDT
Custom Search