Variational methods for multichannel scattering. II. New variant of optimized anomaly-free method and restricted interpolated anomaly-free method

Several methods designed to avoid computational anomalies in the multichannel variational formalism of Kohn are considered. Two new methods are proposed. A new variant of the optimized anomaly-free method ensures that the computed K-matrix is symmetric. This method avoids spurious singularities but may give results that vary discontinuously with energy. A second new method, the restricted interpolated anomaly-free method, avoids both singularities and discontinuities, and produces a symmetric K matrix. Two-channel model calculations show that both new methods have accuracy comparable to the earlier anomaly-free and optimized anomaly-free methods.