It is demonstrated, in calculations on one- and two-electron systems, that K-matrix (real-valued) boundary conditions in the trial wave function in the minimum-variance method can give anomalies at certain energies, while T-matrix (complex) boundary conditions do not. A Monte Carlo procedure is proposed for computing scattering amplitudes in a many-electron system that uses the minimum-variance approach to treat incident and target electrons on the same footing. Successful exploratory calculations on $e^{\mathrm{-}}$-H scattering in the radial limit suggest that this approach may provide a path to direct Monte Carlo scattering calculations on many-fermion systems.

• Received 13 March 1989

DOI:https://doi.org/10.1103/PhysRevA.40.1297