We develop a systematic way to determine an effective nuclear charge Z DR such that the Hartree-Fock results will be significantly closer to the exact energies by utilizing the analytically known large-D limit energies. This method yields an expansion for the effective nuclear charge in powers of (1/D), which we have evaluated to the first order. This first order approximation to the desired effective nuclear charge has been applied to two-electron atoms with Z = 2-20, and weakly bound systems such as H-. The errors for the two-electron atoms when compared with exact results were reduced from ∼0.2% for Z = 2 to ∼0.002% for large Z. Although usual Hartree-Fock calculations for H- show this to be unstable, our results reduce the percent error of the Hartree-Fock energy from 7.6% to 1.86% and predicts the anion to be stable. For N-electron atoms (N = 3-18, Z = 3-28), using only the zeroth order approximation for the effective charge significantly reduces the error of Hartree-Fock calculations and recovers more than 80% of the correlation energy.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry