Isotope Effect in Collision Between Helium Atom and Hydrogen Molecule

Rotationally inelastic He-H₂, D₂, T₂ collision was studied quantum-mechanically. Converged cross sections were calculated by using the close coupling method for relative kinetic energies of 0.01 to 0.54 eV. Born-Oppenheimer approximation was employed to determine the potential surface of He-D₂, He-T₂, and He-H₂. Careful comparison between the cross sections of the isotopically substituted systems was carried out, and the regular changes of the total cross sections of the isotopically substituted He-H₂ colliding systems were obtained.