Radial and Electron Correlation Effects for Helium and Some Helium Like Ions

The radial and electronic correlation effects for intra-electronic shell have been examined within two-electron system, helium atom, and compared with two helium like ions, Li+ and Be++ using the uncorrelated Hartree Fock wave function published by Clementi and Rotti (At Data Nucl Data Tables 14:177, 1974) and the correlated configuration interaction wave function published by Weiss (Phys Rev 122:1826, 1961). Some atomic properties have been studied to exam the radial correlation effects such as; (i) one-particle radial distribution function and one-particle expectation value when k=−2 to 2, (ii) two-particle radial distribution function and two-particle expectation value when k=−2 to 2, (iii) the inter-particle distribution function and inter-particle expectation value when k=−2 to 2, and, (iv) the partial distribution function. In addition to these atomic properties, coulomb hole, partial coulomb hole, the radial correlation for one and two-particles distribution function and the radial correlation energy are very important in studying the physical and chemical properties of these ions or atoms. The results were compared with that calculated in previous published work using partitioning technique.