Subject: TELLING IF TWO CONFORMERS ARE IDENTICAL

From: "E. Lewars" <[email-masked]>
Date: Tue, 21 Feb 1995 21:18:57 -0500

Dongchul Lim asked how one can tell if two conformers are the same.  This is
a special case of how to tell if two isomers are really the same species.
It seems to me a simple approach is (after looking to see that they are
not obviously different) to have your program (MOPAC, GAUSSIAN etc) 
calculate the total internuclear repulsions.  Two species that look the same
and have the same internuclear repulsions (to 6 or more decimals--Hartrees)
are, I would think, extremely unlikely not to be the same.  Many comp.
chem programs calculate internucl. repulsions; if a check job wn't give
that number, then ask for a single-point calc. using a fast method like 
a semiempirical routine.  The actual internuclear repulsin calc. is 
trivial.
Errol Lewars
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