Molecular-state close-coupling theory including continuum states. II. Packet states and couplings for the proton–hydrogen-atom system

Abstract

The preceding paper (I) of this series develops a molecular-state close-coupling theory of ion-atom collisions including the electronic continuum, which is described by packet states spanning it locally. The present paper describes results of computations applying this formulation to the prototype problem of impact ionization in proton–hydrogen-atom collisions, in particular, studies of the properties of the basis states and the nonadiabatic couplings among them. (1) We construct continuum eigenfunctions using a ‘‘quantal momentum’’ or phase-amplitude representation and use this to study construction and properties of continuum packet states, and we show how localization of packet states within a specified interaction region leads to specification of packet widths and/or energies. (2) We verify assumptions made in the derivations given in paper I about nonadiabatic couplings of continuum states, and report computations of coupling matrix elements needed to implement the theory for this system. Subsequent work will present close-coupling calculations using this data.