Milne's differential equation and numerical solutions of the Schrodinger equation. II. Complex energy resonance states

For pt.I see ibid., vol.14, p.4213 (1980). The combination of Milne's theory for calculating bound-state energies and wavefunctions with the complex rotation method yields an appealingly simple and powerful tool for the computation of complex-valued resonance (Siegert) energies and wavefunctions. The method provides an unambiguous assignment of a quantum number n=0,1,... to a resonance state and permits a unified picture of bound-state and resonance properties. The numerical technique is sufficiently fast and stable to enable reliable calculations of higher resonances. This is illustrated for some model potentials. Furthermore the complex energy WKB quantisation is discussed and tested numerically.