https://doi.org/10.1351/goldbook.C00789

The rate constant for a system in which the reactants are in thermal equilibrium at a given temperature. In statistical mechanics the expression 'canonical ensemble' is used to refer to a closed system in thermal equilibrium, the species being present in a statistical distribution. By contrast, a microcanonical ensemble is composed of systems all having the same energy: a canonical ensemble therefore consists of a statistical distribution of microcanonical ensembles. The canonical or thermal rate constant can be obtained from the microcanonical rate constant by summing over the energy, taking into account the statistical distribution.*Source: *

PAC, 1996,*68*, 149. 'A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC Recommendations 1996)' on page 155 (https://doi.org/10.1351/pac199668010149)

PAC, 1996,