A density functional treatment of chemical reactivity and the associated electronic structure principles in the excited electronic states

Global reactivity parameters like the softness and the polarizability and local reactivity parameters like the Fukui function and the local hardness have been calculated for the ground (S-1) and several excited electronic states (P-1, D-1, F-1) of various helium isoelectronic systems (He, Lif, Be2+, B3+, C4+). Only the lowest energy state of a given symmetry is chosen because of the validity of the excited state density functional theory exclusively for this type of states. The softness varies linearly with the cube root of the polarizability for both the ground and the excited states. It has been demonstrated for the first time for the systems studied that a system is harder and less polarizable in its ground state than in any of its excited states. Radial distributions of the charge density, the Fukui function, and the local hardness exhibit characteristic shell structures in both the ground and the excited states.