A triple basis set in Hylleraas coordinates is used to obtain improved variational bounds for the nonrelativistic energy and other properties of He, ${\mathrm{H}}^{-},$ and ${\mathrm{Ps}}^{-}.$ The accuracy, numerical stability, and computational efficiency are compared with recent work based on quasirandom basis sets. The Kato cusp conditions are used to assess the accuracy of the wave functions at short distances.

• Received 12 November 2001

DOI:https://doi.org/10.1103/PhysRevA.65.054501