Explicitly Correlated Extracule Densities for Two-Electron Atoms

摘要

The spherical average d(R) of the electronic extracule density E(R) is the probability density function of finding the center-of-mass radium |r_j + r_k|/2 of any two electrons j and k to be R. For a particular class of correlated wave functions which explicitly include r_(12) terms, a method is presented to obtain the extracule density d(R). The method is applied to the ground-state helium atom and its isoelectronic analogs described by highly accurate Kinoshita wave functions; also near-exact extracule densities d(R), their moments with n = -2 to +4, and electron-electron counterbalance densities d(0) are determined. Comparison of the correlated results with the corresponding Hartree-Fock values shows that the electron correlation shifts the extracule density d(R) from a small to a large R region. Different roles of the radial and angular correlation contributions are also clarified in the electron correlation.