NUCLEAR CUSPS IN THE HSF ELECTRON-DENSITY

The Hiller-Sucher-Feinberg (HSF) identity provides an alternative defi nition for the electron density. The behavior of the HSF electron dens ity in the vicinity of nuclei is analyzed, It is shown that the HSF de nsity possesses nuclear cusps at which its gradient is discontinuous. The discontinuities in the HSF density gradient satisfy a simple equat ion analogous to Kato's electron-nuclear cusp condition. However, in c ontrast to Kato's condition, the electron-nuclear cusp condition is sa tisfied by HSF densities originating from both exact and approximate e lectronic wavefunctions. Several numerical examples are presented to i llustrate this property of the HSF electron density.