Discrete sets of Sturmian functions applied to two-electron atoms

We present a configuration-interaction (CI) method based on Sturmian functions. The components of this CI basis are the solutions of a two-body Sturmian eigenproblem, where the eigenvalues are related to the interacting potential in the two-body equation. Our method accommodates any arbitrary, physically sound, central potential in the Sturmian equations and different adequate asymptotic conditions. Computation of eigenvalues and eigenfunctions is performed by direct numerical discretization of the Sturmian equation. We apply this method to obtain bound states for two-electron systems. We show the convergence of the partial-wave expansion for the ground-states energies of the He atom and the H- ion, and obtain very accurate results that are compared with other recent CI calculations.