Relative magnitude of ``good'' and ``bad'' collisions

We give a more complete presentation of the quantum Langevin (QL) model for neutral-neutral bimolecular interactions and reactions [Gao, Phys. Rev. Lett. \textbf{105}, 263203 (2010)], and use it to provide a general discussion of the relative magnitude of ``good'' (elastic) and ``bad'' (inelastic or reactive) collisions. We show that this relative magnitude is determined by the long-range potential, and has the general characteristics of being ``bad'' at low temperatures and ``good'' at high temperatures.