On the electron-electron coalescence function in Hartree-Fock theory

In many-electron systems, the electron-electron coalescence function I-0(R) represents the probability density that any two electrons are simultaneously located at a position R in three-dimensional space. For the Hartree-Fock wavefunctions. it is shown that the coalescence function I-0(R) is rigorously expressible in terms of the familiar single-electron density rho (r) and spin density S(r). The same is also true in momentum space. (C) 2001 Elsevier Science B.V. All rights reserved.