Subject: Re: MM for Transition Metal Cpds

From: <[email-masked]>
Date: Tue, 11 Jan 94 10:56:10 +0100

Dear Dr. Isaac B. Bersuker,

I aggree with you, really indeed.
Yes, you are right about the electronic effect!

BUT ! Let's see what is a molecular mechanics. It is only a model
without serious chemical background (only with some physical, Hooke law ...)
I do not want to modell electronic interaction, but molecular structure.
I would like to get as fast as I can a correct molecular structure of these
TM complexes (especially, tunsgten carbene complexes). 
With the help of this force field I can model the steric interactions in 
particular reactions.

I prepared lot's of ab initio calculation using GAMESS SBK ECP on our complexes.
A bigger molecule (NAT>30) takes 1 mounth to compute the geometry.
We parametrized the MM method so we can use it.
This same size or bigger mol. takes only 1 or less minutes to compute the 
geometry. (I think you know the differences, advantages and disadvantages, too).

By the way, if someone needs the electronic structure of the TM complex, he/she 
must use the ab initio theory, of course. If you combined these two theory 
(MM and ab initio) you can increase your speed, because you have an 
approximately good structure after the MM minimisation. (I tested!)

Sometimes, you know the electronic structure (approximately, but enough deeply)
only need the mol. structure. Use the METMOD1 force field and your result
will be close to the experimental (RMS error must be less, than 0.1).

Concerning last part of your message, if you can give some seminar in our
school probably we can grant some of your expences.

Something is not clear, just write me!!

	I am waiting your answer!

						Rob