ON THE CHEMICAL POTENTIAL ELECTRONEGATIVITY EQUALIZATION IN DENSITY-FUNCTIONAL THEORY/

General variational principles of the Kohn-Sham (KS) density functiona l theory are interpreted as the corresponding chemical potential/elect ronegativity equalization equations. The unconstrained (ground-state) and constrained (excited) electron configurations are examined for bot h the system global description and for the case of its partitioning i nto mutually closed subsystems, e.g., reactants. The chemical potentia l discontinuity for the integer numbers of electrons at zero temperatu re is stressed, and the KS orbital description of the charge transfer (CT) between reactants is discussed. Using the appropriate ensemble fo rmulation of the KS theory the in situ chemical potential/electronegat ivity difference, the driving ''force'' behind the inter-reactant CT, is linked to the relevant KS frontier eigenvalues of polarized reactan ts.