Molecular orbital
In the early 1950s, Dewar wrote a famous series of six articles on a general Molecular orbital Theory of Organic Chemistry, which extended and generalised Erich Hückel's original quantum mechanical treatments by using perturbation theory and resonance theory, and which in many ways originated the modern era of theoretical and computational organic chemistry. Following Woodward and Hoffmann's suggestion of selection rules for pericyclic reactions, Dewar championed (concurrently with Howard Zimmerman) an alternative approach (which he erroneously felt had been pioneered by M. G. Evans) to understanding pericyclic reactivity based on aromatic and antiaromatic transition states. He did not however believe in the utility of Möbius aromaticity, introduced by Edgar Heilbronner in 1964, and now a flourishing area of chemistry.