A modified Tang–Toennies model for ion–atom potential curves

A modification of the Tang–Toennies potential model suitable for representing heteronuclear ion–atom interactions is proposed. It has the form V(r) =A exp(−br) −B exp(−br/2) −∑3n=2  f2n(r) C2n  r−2n with f2n(r) =1−[∑2nk=0  (br)k/k!]  exp(−br) and displays realistic behavior over a wide range of r. It provides an accurate representation of both spectroscopic data and potentials derived from mobility. Parameters are tabulated for HeNe+, HeAr+, HeLi+, and XeCl−.