On the 'wolfsberg-Helmholz Conjecture' of 'extended- Hückel Theory'

摘要

After having reviewed some pioneer integral approximations closely related to Rüdenberg's expansions of one- and two-electron orbital products, we apply the previously described "Implicit Multi-Center Integration" techniques on Roothaan's "restricted" Fock-matrix components over standard atomic orbital bases. The resulting compact forms are very similar to the well-known "Wolfsberg-Helmholz Conjecture" of "Extended- Hückel Theory," which relates the various off-diagonal matrix elements of "restricted" Fock-type to their corresponding diagonal counterparts. In this way, a "nonempirical Extended-Hückel Theory" can be created.