THE ELECTRONIC, VIBRATIONAL AND ROTATIONAL CONTRIBUTIONS TO THE DIPOLE-MOMENT, POLARIZABILITY, AND FIRST AND 2ND, HYPERPOLARIZABILITIES OF THE BH MOLECULE

Electronic, vibrational and rotational contributions to the dipole mom ent mu, polarizability alpha, and first and second hyperpolarizabiliti es, beta and gamma, are presented for the boron-hydride molecule; stat ic and dynamic rovibrational properties are reported for the first tim e. The electronic contributions are computed ab initio :by finite diff erencing the electronic energy computed: at the Hartree-Fock level of theory, and using various sophisticated correlated methods. Specifical ly these are Moller-Plesset perturbation theory at second order, and f ourth order (including single,double, triple and;quadruple substitutio ns), and the Brueckner variant of the coupled-cluster method including triple excitations; density functional. theory with the B3LYP functio nal is used for comparison. Vibrational land rotational) contributions to the properties are calculated at the Hartree-Fock level of theory; for the vibrational properties, electron correlation is partially inc luded using second order Moller-Plesset theory. Basis set and electron correlation effects on both electronic and vibrational contributions are assessed and discussed. The dependence of the vibrational properti es an, the mechanical and electrical anharmonicity is examined,,and th e two methods used in its computation I;a finite difference-approach a nd a perturbation: theoretic method - are compared and contrasted. A b rief analysis of the frequency dependence of vibrational. contribution s, to alpha(-omega(sigma) ; omega(1)), beta(-omega(sigma) ; omega(1), omega(2)) in the electro-optic Pockels: and second harmonic, generatio n effects;, and gamma(-omega(sigma) ; omega(1) , omega(2), omega(3)) i n the electro-optic Kerr and electric-field-induced : second harmonic: , generation effects, is presented. The electronic results are compare d with literature values believed to the best currently available; agr eement is shown to be acceptable. (C) 1998 American Institute of Physi cs.