Optimized Molecular Exponents on Gaussian Basis Sets for Hybrid Orbitals of Hydrocarbon Molecules

Abstract

To elucidate the adequate molecular exponents for sp3-, sp2-, and sp-hybrid characters, we have performed the optimization for both geometry and Gaussian-type function (GTF) exponents using various hydrocarbon molecules. We have found that the scale factor 1.2 is significant for the p-type GTFs in sp3-carbon, as well as hydrogen. The optimized molecular exponents give a flexible description of σ and π bonds in C-C chemical bonds induced by the difference of hybrid states. We also confirmed the efficiency of our calculation concerning the total energy and geometrical parameters in comparison with the results using the high quality basis sets.