G: Unrecognized representation

From: Andy Dustman <andy %! at !% CCMSD.chem.uga.edu>
Subject: G: Unrecognized representation
Date: Thu, 19 Sep 1996 10:31:37 -0400 (EDT)

 While performing the final population analysis, G94 (Rev C.3) reports:
 Unable to determine electronic state: unrecognized representation
 Here is the input file:
 # MP2/6-31+G* opt=(addredundant,calchffc) nosymm
 propenoate, rotation of carboxylate
 -1 1
 C  0.00000 0.00000 0.0
 C  1.49060 0.00000 0.0
 C  2.19505 1.14001 0.0
 O  -0.62364 1.04495 0.0
 O  -0.68580 -1.18576 0.0
 H  3.29686 1.11914 0.0
 H  1.70087 2.12431 0.0
 H  2.00276 -0.97621 0.0
 3 2 1 4 0.0 S  6 30.0
 After 180 deg of rotation, the point group should again be Cs but G94
 reports C1.  (In fact, it should be indistinquishable from the original
 structure.) The initial population reports an 1-A' electronic state.
 Obviously there is some problem with the symmetry. When I initially ran
 this job, it was without the NOSYMM keyword, and it failed shortly after
 starting the second conformation because of the point group change from Cs
 to C1. With NOSYMM it at least computed all of the structures, though it
 did not produce exactly the requested dihedral angle (usually -0.00005 deg
 off). What is the "correct" way of avoiding these symmetry problems in
 G94? As usual, I will try to post a summary.
 Andy Dustman / Computational Center for Molecular Structure and Design / UGA
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