Alternative definition of exchange-correlation charge in density functional theory

A new definition of the exchange-correlation charge is presented. This char ge is related to the exchange-correlation potential of density functional t heory by the Poisson equation. It is illustrated how, using the Zhao-Morris on-Parr method, this new exchange-correlation charge can be evaluated numer ically, thus providing direct input for the ongoing process of finding impr oved approximate density functionals. Several properties of this new charge , including the sum rule and Coulombic-like behavior, are derived. Both ato mic shell and subshell structures are observed. Exchange-correlation charge s generated from various approximate functionals are calculated and compare d with numerically accurate data for a few atoms. (C) 1999 American Institu te of Physics. [S0021-9606(99)31737-2].