A new version of Johnson's log derivative method for integrating the (nonreactive) Schrodinger equation is described. The new feature is that the log derivative equation is integrated inward (from large r to small r) with initial conditions that correspond to asymptotically incoming (or outgoing) radial waves. The result is that the log derivative function Q(r) (which is now a complex function of r) is a very smooth, nonsingular function (compared to the oscillatory, singular behavior of Q(r) with the usual real boundary conditions), meaning that many fewer grid points are required for its numerical integration. The number of grid points necessary to achieve a given level of accuracy is also only a weak function of the scattering energy E or the mass of the particles. Test calculations for a one-dimensional and a multichannel example illustrate this behavior. 1991 American Chemical Society.
