Approaching the s-wave model ground state energy of He-like atomic ions: results from a model Hamiltonian

Amovilli, Howard and March model Hamiltonian is here extended to an arbitrary interparticle interaction strength. The model remains analytically solvable and the ground state wavefunction with a given, variationally determined, choice of parameters provides an approximate two-electron correlated s-wave function. Results are given for the series of nuclear charges between and 10. More than 60 % of s-wave correlation energy is recovered.