Our research is concerned with the application of quantum mechanical principles to problems in molecular structure and molecular behavior and with work on quantum-mechanical methods to improve their reliability and physical credibility. The general aim is to obtain a correct qualitative description of the behavior of electrons in molecules and to establish quantitative predictions and correlations for important physical and chemical properties of molecules.

Of special interest to us recently has been the density functional theory of electronic structure, wherein the electron density replaces the wave function as the basic quantity in the theory. There results a thermodynamic-like description of an individual molecule, and a whole quantitative language of chemistry featuring concepts such as electronegativity, hardness, and softness, and frontier-electron reactivity indices. Another specific problem on which we are working hard is the calculation of correlation energies of molecules.