Rovibrationally Inelastic Collisions of Ultracold Lithium Dimer

We have calculated cross sections for rovibrationally inelastic collisions of Li$_2 \ A \ (1) ^1 \Sigma_u^+$ colliding with neon and xenon on {\it ab initio} potentials. We find that the inelastic cross section can be very large and increasing at low collision velocity. This behavior is very well modeled as a Langevin process. The total inelastic cross section is a sizable fraction of the total capture cross section, typically about a third. For Li$_2$ - Xe, the total inelastic rate constants are several thousand square angstroms, and level-to-level rate constants are several hundred square angstroms at collision speeds below 1000 cm/s, implying that such collisions might be observable in photoassociated lithium dimer.