Subject: specifying the connectivity in Gaussian

From: Vasile Chis <vchis=at=phys.ubbcluj.ro>
Date: Thu, 08 Apr 2004 09:19:16 +0300

Dear Colleagues,

I am trying to optimize a molecule (with Gaussian) with two charged groups, 
+NH3 and COO-, respectively. However, during the optimization, one of the 
amino hydrogen leaves the nitrogen and bound to one of the oxygen atoms of 
COO group.
In order to preserve the two groups I imposed the same bond length for the 
three NH bonds, but this means a restriction which even if does not led to 
imaginary frequencies, however the corresponding optimized geometry must be 
higher in energy than that in which an NH...O hydrogen bond is allowed.
The Help of the program says that there is a way of giving a specific 
connectivity for atoms, however I was not able to solve my problem. I will 
appreciate very much any help on this topic.

Best regards and Happy Easter for everybody!
Vasile

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Dr. Vasile Chis
"Babes-Bolyai" University
Dept. of Physics
Kogalniceanu 1,
RO-400084 Cluj-Napoca
Romania
Tel: +40 (0)264 405300 ext 5153
Fax: +40 (0)264 591906
e-mail: vchis=at=phys.ubbcluj.ro
http://www.phys.ubbcluj.ro/~vchis
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