Collision Dynamics of Three Interacting Atoms: The Faddeev Equations

An approach to atom-diatom collisions is developed in terms of sums of spin-dependent atomic pair interactions. Elastic, inelastic, atom-exchange, and dissociative collisions are simultaneously considered within the Faddeev formalism, neglecting electronic excitation or ionization. These events may be described as successions of pair-encounters where atomic spins are coupled in singlet or triplet states. At high energies a justification is given for the ``spectator stripping'' model for the reaction A+BC → AB+C and the corresponding probability amplitude is obtained. It is also found that the first correction to this model involves a ``displacement'' mechanism and an effective interaction between A and C.