Applications of a simple molecular wavefunction. Part 1.—Floating Spherical Gaussian Orbital calculations for propylene and propane

Abstract

Calculations have been performed on two rotamers of propylene and three of propane, using the Floating Spherical Gaussian Orbital (FSGO) model developed by A. A. Frost. Extensive parameter searches have been carried out, within certain constraints. Geometrical results are in close agreement with experiment, especially inter-bond angles. The trends in bond lengths for propylene are accurately computed, and further details of its geometry are obtained when symmetry constraints are lifted. Geometry changes that occur in propane on methyl group rotation have also been calculated. The results are discussed in terms of the FSGO basis, which in turn is seen to have good transferability between systems. Some energy changes are not given accurately when unsaturated systems are involved. However, the calculated energy changes are satisfactory when there is a conservation of the number of both single and double bonds. The optimised wave functions are listed fully.