Discovery of Chemical Principles:Symmetry Rules for Degenerate Excitations

Abstract

The article discusses chemical principles such as concept, theorem, rule, and hypothesis, which fulfil the role of so-called milestone in the chemical researches. After overviewing the history of quantum chemistry, the author would like to raise the issue how modern-day theoretical chemists should confront the chemical principles. Next, the symmetry rules for degenerate excitations, which are the chemical principles discovered by the author's group, are described. In particular, this article explains the background of the discovery, the verification by the numerical assessments, and the theoretical interpretation.