I. Borbely et T. Vertse, INHOMOGENEOUS SCHRODINGER-EQUATION FOR ANTI-BOUND AND RESONANT STATES, Computer physics communications, 86(1-2), 1995, pp. 61-66
To avoid instability problems in calculating anti-bound and resonant s
olutions, we propose to represent the wave-function with the sum of it
s large distance asymptotic form and a numerically calculated correcti
on function. The resulting inhomogeneous equation is stable, therefore
it can be solved accurately with standard methods.