Density functional studies of molecular polarizabilities Part 4: the C10H8 molecules azulene, fulvalene and napthalene

We report accurate ab initio studies of the geometries, electric dipole moments and dipole polarizabilities of azulene, fulvalene and naphthalene at both the Hartree Fock and density functional levels of theory. The molecular geometry was optimized in each case at the HF/6-311G(3d,2p) level of theory, and polarizabilities were then calculated at the same geometry but with the addition of diffuse Gaussian primitives. The BLYP density functional formulation was used for the density functional calculations. We also report semi-empirical (AM1, MNDO and PM3) electric dipole and dipole polarizability calculations for comparison; in each case the geometry was optimized before the properties were calculated. The semi-empirical polarizabilities give poor agreement with the ab initio values for the component of the tensor perpendicular to the molecular plane. The calculated mean polarizabilities of the title molecules, together with benzene and fulvene, have been decomposed into contributions from atoms and from groups of atoms. 1997 by John Wiley & Sons, Ltd.