PROBING THE REACTIVITY OF DIFFERENT SITES WITHIN A MOLECULE OR SOLID BY DIRECT COMPUTATION OF MOLECULAR SENSITIVITIES VIA AN EXTENSION OF THE ELECTRONEGATIVITY EQUALIZATION METHOD

The electronegativity equalization method, based on the equalization of the ''effective electronegativity'' of an atom (alpha) in a molecule (chi-alpha = -partial derivative E[N,nu]/partial derivative N-alpha; E = total molecular energy), allows the direct computation of the (atomic) charges q-alpha and the average electronegativity chi-BAR of molecules and solids. We now demonstrate how also other local and global quantities can be calculated directly: the molecular hardness eta-BAR = (partial derivative 2 E/partial derivative N2), the Fukui function (f(r -->) = (delta-2E/partial derivative N-delta-nu)) integrated over the atomic region f-alpha, and the atomic equivalent of the two-variable linear response function (p(1,2) = (delta-2E/dekta-nu-1-nu-2)), p(alpha,beta). It is shown how all these (fundamental) quantities depend on the environment.