OK even maxcyc=500 in total time 339 (100% all processors).
A question about present status of the system. 
Judging from
NSTEP       ENERGY          RMS            GMAX         NAME    NUMBER
      1       4.4840E+09     2.4571E+08     8.2511E+10     C216     9120
 BOND    =   149932.4186  ANGLE   =    46211.6820  DIHED      =     9161.8416
 VDWAALS = *************  EEL     =  -246175.6118  HBOND      =        0.0000
 1-4 VDW =    29126.1421  1-4 EEL =    23905.1720  RESTRAINT  =        0.0000
to
NSTEP       ENERGY          RMS            GMAX         NAME    NUMBER
    500      -2.8141E+05     7.0948E-01     1.8222E+02     C29      4048
 BOND    =    17679.7273  ANGLE   =     1747.5980  DIHED      =     7313.4743
 VDWAALS =    28428.8493  EEL     =  -363382.6658  HBOND      =        0.0000
 1-4 VDW =     2703.4773  1-4 EEL =    24034.2277  RESTRAINT  =       66.8632
 EAMBER  =  -281475.3119
]
(actually 520 steps because I used rst). Which values of ENERGY and GMAX should
be reached with (as in present case) protein-ligand restrained 30.0 before
relaxing the latter? Also, should this minimization be completed with conjugate
gradient, or is this one only to make the process faster?
Thanks
francesco
--- Francesco Pietra <chiendarret.yahoo.com> wrote:
> Great! With
> 
> 1st minimization protein_ligand_pop_box80x80
>  &cntrl
>   imin=1, maxcyc=20, ntmin=2,
>   cut=10, ntb=1, ntpr=1,
>   ntr=1, restraintmask=":77-520, 521",
>   restraint_wt=30,
>   /
> 
> it completed the (small) task (third attempt, in parallel). It should not be
> forgot that I had removed some severe clashes before the third attempt: the
> first attempt would have probably killed even steepest descent (not tried,
> though I could try on demand for maxcyc=20, ncyc=10). Now I'll try
> maxcyc=500,
> otherwise as in the successful run.
> 
> Thanks a lot
> 
> francesco
> 
> 
> 
> --- "David A. Case" <case.scripps.edu> wrote:
> 
> > On Mon, Dec 03, 2007, Francesco Pietra wrote:
> > 
> > > I removed all WAT residues at a distance <=1.5A from POPC residues from
> the
> > > membrane already bearing a cavity. Then inserted the protein-complex and
> > > built the TIP3P box with leap. Then run the minimization again. Starting
> > > energy was 9 orders of magnitude less that previous run (which had
> crashed
> > > because WAT 534 had clashes with POP 24) and gradient and  energy
> decreased
> > > by only 2 orders of magnitude. Again segmentation fault.
> > 
> > Segmentation faults can be very difficult to diagnose, since there can be
> > many
> > causes.  Ordinarily, sander would not segfault on minimization just because
> > of bad overlaps.
> > 
> > What I would do:
> > 
> > 1.  Try a serial minimzation to see if there is some weird parallelization
> > problem.  You are only trying to do a short minimization, so you should
> > reduce
> > your exposure to other problems.
> > 
> > 2.  Only do steepest descent minimization with a bad structure.  Conjugate
> > gradient minimization (which by defaults starts after 10 steps,) can take
> > very
> > large trial steps, which might somehow be violating implicit assumptions
> > about
> > periodicity that leads to memory corruption (just guessing here, but
> avoiding
> > conjugate gradients until you have a better structure is definitely a good
> > idea.)
> > 
> > 3.  If that fails, you will probably have to remove the initial bad
> contacts
> > and see if that helps.
> > 
> > ...dac
> > 
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> 
> 
> 
>      
>
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Received on Wed Dec 05 2007 - 06:07:21 PST