“…Valence bond theory has been used as a framework for modeling chemical reaction dynamics since the early days of quantum mechanics 2, 3, 20–24, 28, 29, 40, 41, 45, 48, 50, 51, 67, 72, 79, 81, 86, 87, 89, 90, 92, 95–99, 101–104, 106, 112, 210–286. In part this may be explained by the fact that valence bond theory often provides a concise description of multireference character, and transition states are more likely than stable molecules to exhibit multireference character.…”