Subject: g98/cosmo (solvent=water) optimization of the anion

From: "Olga Dmitrenko" <[email-masked]>
Date: Mon, 16 Dec 2002 13:12:43 -0500

Hi,
I am trying to optimize 1,2-dihydroxybenzoic acid carboxylate anion in water
at the b3lyp/6-31+g(d,p) level of theory using COSMO model for solvent.
When solvent was =THF, the optimization was complete without any
troubles. Unfortunately, the use of water makes optimization oscillating and
Maximum force is never less 0.016, but Maximum displacement and RMS are
zeros.

- I did increase: TSNUM=250
- I've used opt=gdiis and Iop(1/8=2)

One of my latest control cards looked like:
 #b3lyp/6-31+g(d,p) scrf=(cosmo,read,solvent=water) scf=tight scf(maxcy
 c=400) # IOp(1/8=2) OPT=(readFC,GDIIS) geom=check guess=read

Thus, I have two questions here:

1) Can anybody recommend me some other options within COSMO model (I do not
want
to change the solvent model since a series of calculations is already done)
to force finally the almost optimized anion optimization to converge.

2) Several times I've got at the end of output " Too many tesserae.
Increase the MxTs."
How I can increase the MxTs and what is it?

Any comments will be highly appreciated. Thanks in advance,

Olga
*******************************************
* Dr. Olga Dmitrenko                                            *
* Department of Chemistry and Biochemistry      *
* University of Delaware, Newark                         *
* Delaware 19716, USA                                       *
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