Positron-Hf Collisions: Prediction of a Weakly Bound State

Ab initio molecular $R$-matrix calculations are presented for collisions of low-energy positrons with the hydrogen fluoride molecule as a function of HF internuclear separation. Calculations presented are for $\Sigma$ total symmetry with and without polarization effects. These calculations mirror recent electron-HF scattering calculations by Morgan and Burke. Strong evidence is obtained for the presence of a bound state of the $e^{+}\mathrm{HF}$ system. The experimental consequences of this result are discussed.