On the principle of maximum overlap in molecular orbital theory

Making the usual assumptions typical of elementary Hückel theory including overlap it is shown that the Hückel energy of the two-electron bond is minimized for orbitals having maximum overlap, which yields maximum strength for the straight bond. Analysis of the bond energy for the general A-B bond shows for the molecular orbital description a more complicated dependence on the one-electron exchange-overlap densities of A and B than that recently derived by us in a corresponding valence bond treatment.