#Minimizer Fault?
Has anyone tried minimizing a conjugated non-aromatic system? i.e.,
butadiene or an alpha,beta-unsaturated ketone? Using MM2 (the best of the
given force fields for small molecules(?)) the minimized structure gives
equal bond lengths for both the C1-C2 (or C3-C4) double bond and the C2-C3
single bond. What's going on here? If you submit the structure for
minimization in CNDO/MNDO then the minimized structure seems to be correct
with the calculated single bond length very close to the experimental
value. Haven't yet gotten a reply on this from Autocad (and/or Hypercube –
can't figure out who's going to be responsible for supporting such
questions). Any structure fitting this general pattern seems to suffer the
same problem, i.e., diacetylene also minimizes with all bond lengths equal.
Am I missing something here?