Wavefunctions and Correlation Energies for Two-, Three-, and Four-Electron Atoms

A recently developed method (the GF method) which is equivalent to optimizing the orbitals of a Slater determinant after spin projection has been applied to H−, He, Li+, Be++, Li, Be+,B++, Li−, Be, B+ and C++. These wavefunctions, which can be given an independent particle interpretation, yield better energies than those of the Hartree-Fock method. For example, H− and Li− are correctly predicted to be stable in contradistinction with the Hartree-Fock results. The new correlation energies are tabulated and compared to the Hartree-Fock values. In the case of the two-electron systems the new wavefunctions are nearly at the radial limit, accounting for 93% to 97% of the radial correlation error present in the Hartree-Fock description.