Hartree--Fock energy curves, for BrH+ (X 2PI), KrH+ (X1 Σ+), and RbH+ (X 2Σ+). I. Preliminary calculatons

Restricted Hartree-Fock calculations for the ground electronic states of BrH+, KrH+, and RbH+ have been carried out using carefully selected nominal atomic basis sets for the heavy atoms, supplemented with an additional orbital designed to allow for a better description of atomic distortion at intermediate internuclear separations. A flexible four-function basis set was used on the hydrogen atom. Molecular optimization was carried out for the heavy-atom distortion orbital and also for the hydrogen 2p orbital. The interatomic potentials obtained for the X 2PI state of BrH+ and the X 1Σ+ state of KrH+ show strong molecular binding (i.e., 3-4 eV) relative to the neutral heavy atoms plus a proton. The RbH+ X 2Σ+ calculations give a repulsive interatomic potential with dissociation to Rb+ and a neutral hydrogen atom