RG+Cl(2P) (RG = He, Ne, Ar) interactions:: Ab initio potentials and collision properties

The lowest states of Sigma and Pi symmetry of Rg ... Cl (Rg=He, Ne, Ar) complexes were investigated using the coupled cluster approach with single, double, and noniterative triple excitations (CCSD(T)) in an extended basis set including band functions. The Sigma states possess deeper minima at shorter interatomic distances than the corresponding Pi states. The Sigma-Pi splittings, which for He ... Cl and Ar ... Cl are significantly larger than previously deduced, are mainly due to differences in the exchange repulsion terms. The total energies were dissected into electrostatic, exchange, induction, and dispersion components. The calculated potentials have been used in the calculations of collision properties of Rg ... Cl systems. Absolute total cross sections, spin-orbit quenching rate constants, and diffusion coefficients were evaluated from both the nb initio and previously available empirical potentials. The performance of ab initio potentials in these calculations proved to be very reasonable. (C) 1998 American Institute of Physics.