Use of boundary-condition wavefunctions for bound states, continuum states, and resonances

Supplementing the Schrodinger equation with (artificial) boundary conditions in the traditional manner selects discrete scattering energies and alters bound-state wavefunctions. Two examples of single-channel scattering, electron-He + (1s) and neutral particle-soft shell, illustrate the dependence of phase shifts and bound states upon boundary condition. Comparison of nodal and antinodal boundary conditions tests the termination error of bound-state computations and locates the positions of scattering resonances.