Space-fixed vs body-fixed axes in atom-diatomic molecule scattering. Sudden approximationsRussell T Pack
- Physical and Theoretical Chemistry
- General Physics and Astronomy
The Arthurs and Dalgarno space-fixed (SF) axes formulation of the quantum theory of atom-diatom scattering is compared with the body-fixed (BF) axes formulation of Curtiss using consistent notation to facilitate the comparison. While equivalent, the two theories are not always equally convenient. When rotation is treated in a sudden approximation, the BF formulation has a tremendous conceptual and computational advantage: It allows an infinite-order sudden approximation, independent of the form of the potential energy, which should be very helpful in vibrationally inelastic and reactive scattering problems. Also, a rapid procedure for calculating WKB phase shifts is presented.