Computation of Low-Energy Positronium-Hydrogen Collisions using the Kohn Variational Method

The Kohn variational method is an established method that can provide benchmark calculations for quantum few-body systems. We consider the four-body Coulomb process of positronium-hydrogen (Ps-H) scattering. We improve upon the numerics of prior accurate S- and P-wave Kohn variational calculations of Ps-H elastic scattering [1,2]. For instance, we use a procedure that removes Hylleraas-type terms that lead to linear dependence [3]. In addition to using the Kohn and inverse Kohn variational methods as previously used, we use the generalized and complex Kohn variational methods [4]. We are extending the calculations of Ps-H to include the D-wave.\\[4pt] [1] P. Van Reeth and J. W. Humberston, J. Phys. B \textbf{36}, 1923 (2003).\\[0pt] [2] P. Van Reeth and J. W. Humberston, Nucl. Instrum. Methods B \textbf{221}, 140 (2004).\\[0pt] [3] A. Todd, Ph.D. thesis, The University of Nottingham, (2007), \emph{unpublished}.\\[0pt] [4] J.N. Cooper, M. Plummer, and E.A.G. Armour, J. Phys. A \textbf{43}, 175302 (2010).