ON HUCKEL-HUBBARD CORRELATION DIAGRAMS

In order to contrast the Huckel molecular orbital theory (HMO) with a simple valence bond theory (Heisenberg-Dirac model), which are two opp osite asymptotic limit cases of the Hubbard model, Hubbard problems ha ve been solved for four sites systems with four electrons. The Huckel- Hubbard correlation diagrams, where employs a parameter: U/t, have bee n obtained for these system. From correlation diagrams some interested results have been deduced in detail.