Extended basis set studies of hydrocarbon molecular orbital energies

Abstract

Ab initio molecular orbital theory with three extended basis sets (4-31G, 6-31G, 6-31G *) has been used to study some simple hydrocarbons. Results are presented for propane, 1,3-butadiyne and several of the isomers of the C 4H 4 and C 4H 6 systems. The inclusion of polarization functions (basis 6-31G *) leads to relative energies within 3 kcal mol −1 of the available experimental data. Results are also presented for isodesmic energy comparisons, including bond separation energies.