Computation of Coulomb and exchange radial intracule densities

The computation of the Coulomb and exchange components J(u) and K(u), respe ctively, of the Hartree-Fock radial intracule density within the PRISM appr oach is discussed. Formulae are presented for the even-origin derivatives o f these quantities and for the even-order moments of J(u). For molecular sy stems, we demonstrate that J(u) has, as expected, long-range nature compara ble with the molecular extent but, in contrast, that K(u) is relatively sho rt-range, with delocalisation effects providing additional structure and en hancing the range of the intracule. (C) 1999 Elsevier Science B.V. All righ ts reserved.