Lifetime and decomposition pathways of a chemically bound helium compound

HHeF, a first predicted chemically-bound helium compound, is a metastable s pecies that disintegrates by tunneling through energy barriers into He+HF a nd H+He+F. The reaction paths for these decomposition processes are calcula ted with single-configurational Moller-Plesset (MP2) and multiconfiguration al quasidegenerate MCQDPT2/MCSCF(10,6) electronic structure methods. The li fetime of HHeF, estimated using a one-dimensional model along the minimum e nergy path and the semiclassical WKB approximation, is more than 120 ps, th at of DHeF is 14 ns. The relatively long lifetimes are encouraging for the preparation prospects of this helium compound. (C) 2001 American Institute of Physics.