Subject: MM3 in TINKER

From: [email-masked] (Christoph Etzlstorfer)
Date: Fri, 6 Jun 1997 15:57:09 +0100

Rencently I downloaded the modeling package TINKER which contains MM3. When
calculating the structure of 4,5-dimethylphenantrene I found a torsion
angle 4-12-13-5 (the angle on the ringsystem between the methylgroups) of
20.8 degree. In the paper in which MM3 on conjugated hydrocarbons is
presented (J. Comp. Chem. 11, p. 868 (1990)) it is 31.9 degree with MM3 and
31.5 degree with X-ray. The structure in the inputfile had a torsion angle
of about 35 degree.

Does anyone have any experiences with MM3 in TINKER?

###################################################################
Dr. Christoph Etzlstorfer       Phone:  *43-732-2468-750
University of Linz              Fax:    *43-732-2468-747
A-4040 Linz               E-mail: [email-masked]
Austria                   http://ocwww.chemie.uni-linz.ac.at
###################################################################

---

From: [email-masked] (STEPHEN ANDRUSKI)
Date: Fri, 6 Jun 1997 12:02:38 -0500

I do not have any experience with MM3 in TINKER, but I ran a quick 
     calculation with Alchemy 2000 which also has an implementation of MM3. 
      The angle in question minimized to -31.6 degrees which is in very 
     good agreement with the X-ray structure and the previously published 
     MM3 value.
     
     Something in TINKER's implementation must be off.
     
     Dr. Stephen W. Andruski
     FMC Corporation
     [email-masked]