Subject: Problems with GAMESS convergence

From: Connie Chang <[email-masked]>
Date: 24 Mar 2003 22:10:05 -0500

Hi --

I am trying to do a geometric optimization on a molecule with 140
atoms.  But my process ends abnormally because SCF convergence hasn't
been achieved.  I'm using GBASIS = PM3 and SCFTYP=RHF.  I've increased
the MAXIT to 1000 (recompiling the source code) and I have made the
convergence criterion less stringent with the line $SCF CONV=2d-3
DAMP=.TRUE. $END

I've also made the geometric optimization less stringent (although I
don't think this is the problem since it's failing at the SCF
convergence level) with the line $STATPT OPTTOL=.0001 $END

Does anyone know of any other ways to get my molecule to converge?  I've
also tried restarting the job using  GUESS=MOREAD and the VECTOR frm the
.dat file; but I'm not sure what to put down for number of orbitals --
NORB.  Would it be 280 since I have 140 atoms?  Or something else?  

Any other advice or recommendations would be appreciated.  I'm at a
loss!

THanks,
Connie