Modification of the superposition of correlated configurations method

Abstract

Introduction of a modified correlation factor in the place of r: eliminates the problem of multiple infinite summations in Hamiltonian matrix elements. Calculations performed for several He states show that the introduction of the modified correlation factor does not change energies of the states by more than 1 cm-'.

Evaluation of two‐center, three‐ and four‐electron integrals over Slater‐type orbitals in elliptical coordinates

“…A number of exact results for the energy of the ground and excited states of the helium atom 6, 7 as well as the isoelectronic series of the lithium atom 8–10 has been obtained by means of the Slater‐type orbitals as the basis of one‐electron functions. In those cases, the most important is the fact that the problem of evaluation of the integrals in the basis of Slater orbitals for atoms (as one‐center systems) is completely solved 6 (see also 11).…”