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

In many-electron systems, the electron–electron coalescence function I0(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 I0(R) is rigorously expressible in terms of the familiar single-electron density ρ(r) and spin density S(r). The same is also true in momentum space.