Molecular properties of N2 and CO2 as functions of nuclear geometry: Polarizabilities, quadrupole moments, and dipole moments

A b initio static polarizabilities, quadrupole moments, and electronic energies of ground state N2 and CO2 have been calculated self-consistently as functions of nuclear geometry in the Hartree–Fock approximation using the finite-field method. In addition, permanent dipole moments for the infrared-active vibrational modes of CO2 have been determined. For N2, the effects of electron correlation on these molecular properties have been studied by performing generalized valence bond (perfect pairing) calculations with the same basis sets as were used in the Hartree–Fock calculations. These basis sets are constructed from energy-optimized contracted sets of nucleus-centered Gaussian-orbitals to provide a flexible representation of the entire molecular charge cloud, including the highly polarizable outer regions. Results of these calculations are compared with experimental and other theoretical values where possible.