Theoretical prediction of the lifetime of the metastable helium compound: HHeF

Ab initio electronic structure calculations at the multi-reference configuration interaction level of theory have been performed for the He-containing compound H–He–F. The calculations indicate that the linear H–He–F molecule is metastable with a barrier of 0.224 eV for the H–He–F→H+He+F dissociation and a barrier of 0.448 eV for H–He–F→He+HF. A global potential energy surface for the ground state has been developed on the basis of extensive grid point calculations and three-dimensional wave packet calculations were carried out to extract the information of resonance states. We have found that the lowest resonance state has a lifetime of only 157 fs.