AMBER: convergence criterion not reached

From: Jena M <jeninhas.hotmail.com>
Date: Tue, 3 Jul 2007 00:53:22 +0100

Hi all,
 
I want to move a ligand toward a protein residue in various steps using distance restraints, and then calculate the energy at each step through a minimisation. I want to use a strict 0.0001 kcal/mol convergence criterion. However at the first step the minimisation ended with the following message:
 
     .... RESTARTED DUE TO LINMIN FAILURE ...
 
     ***** REPEATED LINMIN FAILURE *****
 
 
                    FINAL RESULTS
 
 
 
   NSTEP ENERGY RMS GMAX NAME NUMBER
    822 -5.0298E+05 6.1915E-04 1.0122E-01 HB2 10744
 
 BOND = 39734.7517 ANGLE = 1487.9524 DIHED = 5686.4433
 VDWAALS = 102545.9807 EEL = -677189.7052 HBOND = 0.0000
 1-4 VDW = 2262.0803 1-4 EEL = 22489.1732 RESTRAINT = 1.0329
 EAMBER = -502983.3235
 NMR restraints: Bond = 0.038 Angle = 0.000 Torsion = 0.000
 
I read in amber list that this usually happens when shake is used but I didnīt use it. My input file is the following:
 
GGT minimizacao, full-conjugate gradient minimization
 &cntrl
  imin = 1,
  ntmin = 0,
  maxcyc = 10000,
  ntb = 1,
  nmropt=1,
  ntr = 1,
  restraint_wt=200.0,
  restraintmask='!:566, 667 <:10 | (!:566,667)',
  cut = 10
 /
 &wt type='DUMPFREQ', istep1=1 /
 &wt type='END' /
DISANG=d1.restraint
DUMPAVE=d1.result
 
#distance restrainst
&rst iat=566,667, r1=0.0, r2=8.0, r3=8.0, r4=100.0, rk2=50., rk3=50.,
 iresid=1,
 ATNAM(1)='SG',
 ATNAM(2)='C20',
/
 
I have checked the minimized structure but I didn’t see anything wrong with atom 10744.
Does anyone has any suggestion about what can I modify in my input file to reach the 0.0001 kcal/mol convergence criterion withouth this problem?
 
Thanks
Jena
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Received on Wed Jul 04 2007 - 06:07:25 PDT
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