The Linear Two-State Landau-Zener Model

摘要: The two-state nonadiabatic-coupling model discussed in this chapter was the first attempt to describe nonadiabatic coupling over small range of interatomic separations near pseudocrossing or crossing adiabatic terms. Since time when Landau obtained analytical expressions for transition probabilities weak [8.1] and near-adiabatic [8.2] cases, Zener [8.3] Stueckelberg [8.4] found solutions strong semiclassical approximation, has been widely used interpretation various experiments on atomic ionic collisions [8.5–9]. Moreover, Landau-Zener formula often beyond validity both as such approximations adopted solution equations. In particular, by Landau, were making assumption that motion system nonadiabaticity region quasi-classical. This imposes a lower limit nuclear velocity, condition extent interaction be an upper limit. However, velocity variations satisfying constraints appeared insufficiently wide application theory certain problems. stimulated publishing many papers attempting clarify applicability model, widen it much possible, even remove restrictions imposed initial formulation [8.10–12].