The second order reduced density matrix and the chemical bond

The Fermi hole is described as a function of one electron which is parametrically dependent on the position of a 'probe electron'. The sensitivity of the Fermi hole to the position of the probe electron is described by the Fermi hole mobility function. Localized molecular orbitals analogous to Wannier functions may be determined from the Fermi hole of a selfconsistent field electronic wavefunction. Comparison of the Fermi hole mobility function for a self-consistent field wavefunction to that of a free-electron gas may be used to partition a molecule into electronic domains. The Fermi hole and Coulomb hole of a correlated wavefunction may be specified by natural representations which depend on the position of the probe electron