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.