The Hückel molecular orbital method is a quantum mechanics approach for calculating the energies of molecular orbitals of π electrons in conjugated hydrocarbon systems, such as ethylene, benzene, and butadiene.
It was proposed by Erich Hückel in 1930, and, subsequently extended and improved but other scientists. It provides the theoretical foundation for Hückel’s rule for the aromaticity of (4n + 2) π electron cyclic, planar systems. These are some of my slides on this topics. In the future, I will add some more explanations.