Spin‐free quantum chemistry. XVII. The Hückel–Hubbard theory and the Woodward–Hoffmann rules

AbstractWe have developed a many‐body version of Woodward–Hoffmann theory which is capable of rapid computation of π‐electronic surfaces. This theory, called the Hückel–Hubbard theory, employs Hückel parameters as reaction coordinates and the Hubbard parameter for electron repulsion. We apply it to the cis‐trans isomerization of ethylene and to several pericyclic reactions.