Quoting Cenk Andac <cenk_andac.yahoo.com>:
> I have been working on computing RESP charges for an
> aminoacid-copper complex using redII and GAMESS.
> I prepared a PDB file for the complex in LEAP and
> relaxed it using LEAP's relax option.
> However, GAMESS has failed optimizing the complex
> strucuture for more than 2 days.
GAMESS optimization criteria set up in R.E.D. are very tight to get reproducible
RESP charges (+/-.0001) indepently of the initial structure. This might be
interesting in some cases (organic molecules).
You might not need this accuracy in particular for inorganic complexes...
You could modify R.E.D.-II to decrease these thresholds, i.e. something like:
$CONTRL ICHARG=0 MULT=1 RUNTYP=OPTIMIZE
MAXIT=200 UNITS=ANGS MPLEVL=0 EXETYP=RUN
SCFTYP=RHF
COORD=UNIQUE $END
$SCF CONV=1.0E-08 FDIFF=.F. $END
$SYSTEM TIMLIM=50000 MWORDS=8 MEMDDI=0 $END
$STATPT NSTEP=200 OPTTOL=1.0E-05 $END
$BASIS GBASIS=N31 NGAUSS=6 DIFFSP=.F.
NDFUNC=1 NPFUNC=0 $END
$GUESS GUESS=HUCKEL $END
> Obvioulsly the
> structure does not converge to 1.E-8.
Do you mean SCF converge ?
> I know that RED-II and GAMESS have passed a test run
> with NMethylacetamide provided in RED-II manual. I
> have also triple checked connectivity and ATOM
> information in the PDB file for the complex. There is
> no problem with that either.
> The problem is I think with atomic coordinates. I
> guess I need to start out with a converged structure
> (~1.E-8) of the complex.
Once you will have obtained this set of optimized Cart. coordinates (I heard
Q-Chem (commercial) is pretty good for metal complexes), you can apply
http://www.u-picardie.fr/labo/lbpd/RED/FAQ-II.htm#2
to transform the format of the QM output to make it compatible with
R.E.D.-I/II/III (to make it GAMESS|Gaussian like).
Regards, Francois
--
• F.-Y. Dupradeau •
DMAG EA 3901 & Faculte de Pharmacie, Amiens, France
••••
http://www.u-picardie.fr/labo/lbpd/FyD.htm
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Received on Tue Sep 06 2005 - 10:53:01 PDT
