Standing-wave rearrangement scattering formalism for multiarrangement quantum-defect theory

Nonrelativistic time-independent quantum scattering theory for collisions w ith rearrangements is investigated for standing-wave solutions, principal-v alue Green's operators, and related reaction operators. The solutions corre sponding to different arrangement configurations are obtained directly from the properties of the noninvertible Green's operators, without having reco urse to arguments based on unitarity. By casting multichannel quantum defec t theory (MQDT) as a particular case of standing-wave scattering, a formali sm for multiarrangement MQDT is presented and methods for calculating the w ave functions and reaction matrices are proposed. The formalism is illustra ted in connection with current work on ionization and dissociation in H-2. [S1050-2947(99)07003-1].