Adiabatic quantum trajectory capture for cold and ultra-cold chemical reactions

International audienceThe Langevin capture model is often used to describe barrierless reactive collisions. At very lowtemperatures, quantum effects may alter this simple capture image and dramatically affect the reactionprobability. In this paper, we use the trajectory-ensemble reformulation of quantum mechanics, asrecently proposed by one of the authors (Poirier) to compute adiabatic-channel capture probabilitiesand cross-sections for the highly exothermic reaction Li + CaH(v = 0, j = 0)!LiH + Ca, at low andultra-lowtemperatures. Each captured quantum trajectory takes full account of tunneling and quantumreflection along the radial collision coordinate. Our approach is found to be very fast and accurate,down to extremely low temperatures. Moreover, it provides an intuitive and practical procedurefor determining the capture distance (i.e., where the capture probability is evaluated), which wouldotherwise be arbitrary