This expression refers to the assumption, essential to conventional transition-state theory
that the energy of the system may be expressed as the sum of components associated
with different degrees of freedom
. In transition-state theory it is assumed that the energy of the motion of the system
through the dividing surface
of the potential-energy surface
is separable into various components. In many practical calculations it is assumed
that the energy of the system is separable into electronic, vibrational, rotational
and translational energy.
PAC, 1996, 68, 149
(A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC
on page 186
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. https://doi.org/10.1351/goldbook