A development of transition-state theory in which the dividing surface is varied so as to minimize the rate calculated for a fixed energy. The rate expressions obtained in a microcanonical treatment can be integrated over the energy, taking into account the statistical distribution over energy states, so as to give the canonical, or thermal, rates.
Source:
PAC, 1996, 68, 149. 'A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)' on page 173 (https://doi.org/10.1351/pac199668010149)