High Precision Hy-CI Variational Calculations for the Ground State of Neutral Helium and Heliumlike ions

Abstract

Hylleraas-Configuration Interaction (Hy-CI) method variational calculations with up to 4648 expansion terms are reported for the ground S state of neutral helium. Convergence arguments are presented to obtain estimates for the exact nonrelativistic energy of this state. The nonrelativistic energy is calculated to be -2.9037 2437 7034 1195 9829 99 a.u. Comparisons with other calculations and an energy extrapolation give an estimated nonrelativistic energy of -2.9037 2437 7034 1195 9830(2) a.u., which agrees well with the best previous variational energy, -2.9037 2437 7034 1195 9829 55 a.u., of Korobov[1], obtained using the universal (exponential) variational expansion method with complex exponents[2]. In addition to He, results are also included for the ground S states of H−, Li, Be, and B.

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Cite this paper

@inproceedings{SimsHighPH, title={High Precision Hy-CI Variational Calculations for the Ground State of Neutral Helium and Heliumlike ions}, author={James S. Sims and Stanley A. Hagstrom} }