Two-parameter wavefunction for the ground state of the helium isoelectronic sequence

Abstract

A simple two-parameter wavefunction for the ground state of two-electron atoms has been obtained by introducing variational parameters in the Hamiltonian rather than in the trial wavefuncLon The energy eigenvalues have been calculated for atoms with nuclear charge Z in the range i < Z < 12. The binding energies so obtained are observed to be better than the corresponding one-parameter {only screening} values, and are in reasonable agreement with very accurate multiparameter results reported by earlier workers. The method proposed is only easily extendable to those configurations in which both the electrons occup> the same orbital. © 1995 IOP Publishing Ltd.