Semiempirical, Pseudopotential Calculation of Alkali–Noble-Gas Interatomic Potentials

A relatively simple semiempirical method is suggested for calculating interatomic potentials of ground and low-lying excited states of diatomic systems composed of an alkali atom and a ground-state noble-gas atom, and its applicability to other systems is discussed. Two types of interaction are included: an electrostatic interaction which yields the asymptotic R−6 behavior characteristic of van der Waals potentials, and a pseudointeraction which represents the effect of the Pauli exclusion principle on overlapping electron states. For the electrostatic interaction, the noble-gas atom is treated as a polarizable dipole with two parameters, namely a polarizability α and a “radius” r0. The value of r0 is chosen by adjusting the depth of the ground-state well to agree with recent scattering data. To determine the interatomic potentials, the total Hamiltonian including spin–orbit coupling is diagonalized in a limited basis set of atomic orbitals. Results are presented and compared with previous calculations and experiments.