Almost-adiabatic collisions of quantum systems

Abstract

Expressions are derived for corrections resulting from a small variation of the “slow” internal degrees of freedom during an almost-adiabatic quantum collision. First-order non-adiabatic contributions to the scattering wave function and scattering T-matrix element are derived making use of (a) Wronskian surface terms, and (b) converging factors. Advantages of method (a) are indicated. Modifications of the expressions necessary to include a possible projectile intrinsic spin are described. A one-dimensional model illustrating the range of validity of the adiabatic approximation is presented.