Ab initio ground state potential energy surfaces for Rg-Br2 (Rg = He, Ne, Ar) complexes

High-level ab initio molecular electronic structure calculations are performed for Rg-Br-2 (Rg=He, Ne, Ar) complexes at CCSD(T) (coupled cluster using single and double excitations with a noniterative perturbation treatment of triple excitations) level of theory. Specific augmented correlation consistent basis sets are used for each noble atom (Rg), supplemented with an additional set of bond functions. Effective-core potentials (ECPs), augmented with diffusion (sp) and polarization (3df ) functions, have been employed for the bromine atoms. For all complexes, the CCSD(T) potential energy surfaces (PESs) show double-minimum topology, with wells at both linear and T-shaped configurations; the linear minimum is found to be deeper than the T-shaped one. Vibrational corrections are taken into account for all the complexes and their effects in the stability of the linear and T-shaped conformers are examined. For each complex and each configuration (linear and T-shaped), R-e equilibrium intermolecular distances, D-e and D-0 dissociation energies, are evaluated and compared with previous theoretical and/or experimental results. (C) 2002 American Institute of Physics.