Ab initio studies of the dipole polarizabilities of conjugated molecules: Part 3. One electron properties, dipole polarizability and first hyperpolarizability of quinoline and isoquinoline

Abstract

We report an ab initio study of the molecular geometry, certain one electron properties, the static dipole polarizability and the first hyperpolarizability of quinoline and of isoquinoline. Calculations were done using the analytic coupled perturbed Hartree-Fock (CHF) method with a careful choice of atomic orbital basis set. Electron correlation was treated at the MP2 level of theory. The electric dipole moment, nuclear quadrupole coupling constant and the asymmetry parameter at the N nucleus, together with the static molecular polarizabilities were calculated at the HF and MP2 levels of theory. We used the STO/6-31G *, STO/6-31G ** and STO/6-31+G basis sets at the fully-optimized HF/3-21G ** and HF/6-31G ** molecular geometries. We show that at HF level, the STO/6-31+G extended split valence basis set with diffuse sp functions on the heavy atoms, gives one electron properties and dipole polarizabilities that are in excellent agreement with the corresponding experimental data. The effect of geometry optimization on these properties is analyzed as is the effect of electron correlation when treated at the MP2 level of theory.