Nh. March et al., Nuclear cusp conditions for components of the molecular energy density relevant for density-functional theory - art. no. 012520, PHYS REV A, 6301(1), 2001, pp. 2520
Nuclear cusp conditions are obtained for the full electron-electron interac
tion energy density as well as for the exchange and correlation energy dens
ities of density-functional theory. Their form is the same as the form of t
he well known Kato cusp condition for the electron-number density. All thes
e cusp conditions are valid for both the ground and excited states of a mol
ecule or solid.