A direct evaluation of regional Fukui functions in molecules

A simple formalism to obtain regional Fukui functions is presented. The model is based on an exact relationship between this local reactivity descriptor and the frontier molecular orbitals. Within this approach, it becomes possible to define an orbital Fukui function that directly yields the condensed-to-atom quantity. By this procedure, we avoid additional calculations of the anion or cation associated with the molecule, thereby maintaining the spin multiplicity of the system. It is shown that our proposed definition of the Fukui function mainly contains symmetry information about the molecular system. The proposed methodology is tested against several benchmark model reactions that are well documented in the experimental and theoretical literature.