Abstract: | Under the Kohn–Sham theory, we examine solutions for the equations δTS/δρ(r) = 0 and δTS/δρ(r) = νKS(r) that link the chemical potential of the electronic system with the effective Kohn–Sham potential through μ = νKS(r) + δTS/δρ. For single ions, we identify the chemical potential with the eigenvalue of the frontier orbital when the atom is in the limit of full ionization. For the case of cations, the chemical potential is found above ?(I + A)/2 and has the property of grouping ions with the same chemical characteristics. For the anion instead, the chemical potential is fixed at the ionization energy. By solving the above equations numerically, two radial points called r? and r+ are obtained and compared with the Shannon–Prewitt ionic radius. Moreover, we found for the halide series, that r? is numerically equivalent to rm, the radii where the electrostatic potential has its minimum, but shows different behavior upon charge variation. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 |