The discussions on MOPAC pointed up the presence of the two values for the bohr radius. Someone pointed out differences of .01 kcal or less that were attributed to severak possible reasons. Upon changing the bohr radius to 0.529177, and the associated reciprocal I found 0.32 kcal difference in our local benchmolecule. Took 10% longer to run to the same gradient convergence criterion with .529177, etc... FYI John McKelvey E Kodak