Subject: Q: MM2/3 and hetero-PI-systems

From: [email-masked] (Norbert Mueller)
Date: Tue, 1 Mar 1994 12:57:54 +0100

May I ask the CCL community for a little help in choosing the right
program version for our projects - I must admit I am a bit confused.

We have been doing force field calculations on heterocyclic and
condesed carbocyclic aromatic systems including conjugated carbonyl
and Schiff base groups for some time using a hoe-brew forcefiled at
first and MM2+, a derivative of MM2 that includes part of the PI-
electron calculations from MMPI. These programs have undergone several
ports (mainly forced by changes in the available environments) and
modifications to include some more hetero-atoms.
Now we have reached a stage, where maintaining these programs has
become rather involved. So we are considering to switch to a state of
the art program, which should sport the following features.

Pi-electron calcaulation including hetero-atoms (at least O and N)
        both as part of an aromatic system and as substituents
Good parametrization of heats of formation,
        vibrational spectra are not required
The program must be available in source form at a reasonable academic
rate (QCPE).

The two choices we have been considering are
MM2(91) and MM3(?)

Can those with experience give us some clues on the aptness of either
of these (or alternatives) give us some recommendations?

Thank you, I will summarize if there is interest in this

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Norbert Mueller - Institut f. Chemie, Johannes Kepler University
                  A-4040 Linz Austria
e-mail: [email-masked] (POP3 - Eudora - preferred)
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"True science teaches, above all, to doubt, and to be ignorant."
                               Miguel do Unamuno