Rotationally inelastic collisions of LiH (X 1Σ +) with H: State-to-state inelastic rotational cross-section

Abstract

The potential energy surface describing the interaction between the hydrogen atom and the rotating LiH molecule has been calculated very accurately and presented in our previous work (J. Mol. Struct. (THEOCHEM) 678 (2004) 11). The rigid rotor potential already fitted analytically and expanded in terms of Legendre polynomials, is employed here to evaluate the pure state-to-state rotational cross-sections over a range of energies of astrophysical interest varying from 10 to 3000 cm −1. An exact close coupling and CS calculation of the state to state rotational cross-section was done first in the range of small energy, from 10 to 100 cm −1. The comparison of both results shows the good agreement between them and leads to a generalisation of such calculation for higher energy using the CS approximation. We determine the state to state rotational cross-section for transitions from j=0, 1, 2, 3, 4 to all accessible final states j′, at total energy varying between 10 and 3000 cm −1. The presented cross-sections were found to be very large even for low energy and large Δ jj′ . Thus indicates the important probability to produce the heated LiH molecule in excited states by collisions with H and explain the strong anisotropy discussed in our previous paper.