AB-INITIO AND ANALYTICAL POTENTIAL-ENERGY FUNCTIONS OF K2NA+,

Ab initio variational calculations were performed on K2Na+ at the MP4 (single, double and quadruple substitutions) level of theory using (20 s, 14p, 2d, 1f)/[13s, 8p, 2d, 1f] and (17s, 11p, 2d, 1f)/[10s, 6p, 2d, 1f] basis sets for potassium and sodium respectively. The 1s, 2s and 2p orbitals on potassium, Is orbital on sodium and their virtual count erparts were not included in the correlation treatment. A 63 discrete potential energy hypersurface was generated using a vibrational t-coor dinate system. The minimum energy structure is of C-2v symmetry with a bond length and included bond angle of 3.855 Angstrom and 73.9 degree s respectively. From this hypersurface analytical potential functions were obtained using power series expansions, which will be embedded in an Eckart-Watson rovibrational Hamiltonian and from which rovibration al eigenfunctions and eigenenergies will be calculated.