Generalized Hylleraas Calculation of Positron-Hydrogen Scattering

A rigorous-bound calculation is performed of positron-hydrogen scattering below the positronium pickup threshold. The correlation function is a generalized Hylleraas function with three nonlinear parameters which includes a virtual-positronium factor explicitly. Phase shifts are calculated as a function of the number of linear parameters using up to 84 terms. Converged phase shifts can be extrapolated to four significant figures. At three of the seven values of $k$ computed, the results are found to disagree slightly but significantly from Schwartz's results. Final phase shifts are estimated to be accurate to \ifmmode\pm\else\textpm\fi{} 2 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}4}$ rad.