Theoretical Studies of H + H2 Rotationally Inelastic Scattering

Abstract

Rotationally inelastic H,H₂ scattering, without rearrangement, was studied quantum mechanically in three dimensions. A close‐coupling technique was employed with a basis set consisting of unperturbed molecular functions. The resulting coupled differential equations were solved numerically by a technique recently developed by Gordon. The Porter‐Karplus semi‐empirical potential surface was used to represent the H₃ system. Cross sections were calculated for relative kinetic energies of 0.05 to 0.50 eV. Various approximations were investigated and their effect on the inelastic cross sections were computed; they include variation of the number of terms in the expansion of the exact wavefunction, exclusion of high‐order asymmetry contributions to the potential surface, treating the H₂ target as a rigid rotor fixed at some specified internuclear distance, and modifying the long‐range behavior of the Porter‐Karplus surface. Differential cross sections in the helicity representation were also computed for various energies.