Analytical potential energy surface and quasi-classical dynamics for the reaction LiH(X,1Σ+)+H(2S) → Li(2S)+H2(X,1Σ+g)

A potential energy surface has been derived using ab initio and spectroscopic data for the lowest 2A′ state of LiH2. Quasi-classical trajectories have been carried for the astrophysically important reaction LiH(X,1Σ+)+H(2S) → Li(2S)+H2(X,1Σ+g). Between 150 and 4000 K the rate is 2–6×10−10 – 6×10−10 cm3 molecule−1 s−1 and a satisfactory analytical fit to this is 8.4×10−13Texp(−0.0004T) while below 150 K the rate goes as 4.36×10−11 T0.28 cm3 molecule s−1 which is close to that expected from the long-range behaviour of the electronic energy. The reaction is exothermic by about 2 eV which is disposed of largely in high vibrational states of H2(X,1Σ+g).