Ionization energy correlations for alkyl-substirured chromophores

A correlation algorithm for ionization potentials of alkylated molecules is presented and tested. This algorithm treats the situation in which the chromophore X is held constant while the substituent S is varied, it provides an expression for the ionization potential as a function of substituent molecular parameters, and it gives a faithful representation of the experiment. A very concise derivation of the correlative equations is also presented. This derivation follows from the imposition of specified model assumptions upon the superposition of Koopmans' theorem and the antisymmetrized molecular spin-orbital approximation.