Application of Huckel theory to resonance stabilization

The observation of resonance stabilization in aromatic molecules is a test case for Huckel theory. Cyclie molecules with 4n + 2 pi electrons have resonance stabilization that is greater than the linear molecules with the same number of pi electrons. This aromatic stabilization may account for the very large number of aromatic molecules. In the brief presentation we show the comparison of the Huckel theory calculation of the pi stabilization of benzene and hexatriene

Huckel theory applied to benzene

In the presentation we give a further demonstration of the application of Huckel theory to the calculation of the benzene energy levels. Benzene belongs to the D_6h point group. This high symmetry greatly simplifies the secular determinant. Instead of a 6x6 the symmetry blocks end being 2 2x2 and 2 1x1. A 1x1 is just a single calculation that gives the energy. Thus, a problem that is nearly intractable by hand becomes quite easy to do in 10 minutes.

Huckel theory applied to hexatriene

The hextriene problem is a bit more difficult since it has lower symmetry than benzene. However, the presentation shows that the C_2h symmetry permits the 6x6 secular determinant to be factored into 2 3x3 determinants. The Huckel method reduces the polynomials to a very simple form, which readily permits graphical solution.