Intramolecular Dynamics Dynamical Theories

A situation that arises from the intramolecular dynamics of A and completely distinct from apparent non-RRKM behaviour is intrinsic non-RRKM behaviour [9], By this, it is meant that A has a non-random P(t) even if the internal vibrational states of A are prepared randomly. This situation arises when transitions between individual molecular vibrational/rotational states are slower than transitions leading to products. As a result, the vibrational states do not have equal dissociation probabilities. In tenns of classical phase space dynamics, slow transitions between the states occur when the reactant phase space is metrically decomposable [13,14] on the timescale of the imimolecular reaction and there is at least one bottleneck [9] in the molecular phase space other than the one defining the transition state. An intrinsic non-RRKM molecule decays non-exponentially with a time-dependent unimolecular rate constant or exponentially with a rate constant different from that of RRKM theory. 

The above describes the fundamental assumption of RRKM theory regarding the intramolecular dynamics of A. The RRKM expression for k E) is now derived. 

Intramolecular dynamics and chemical reactions have been studied for a long time in terms of classical models. However, many of the early studies were restricted by the complexities resulting from classical chaos, Tlie application of the new dynamical systems theory to classical models of reactions has very recently revealed the existence of general bifurcation scenarios at the origin of chaos. Moreover, it can be shown that the infinite number of classical periodic orbits characteristic of chaos are topological combinations of a finite number of fundamental periodic orbits as determined by a symbolic dynamics. These properties appear to be very general and characteristic of typical classical reaction dynamics. 

Rudolph A. Marcus is perhaps the most famous theoretician to be raised in Canada. He has received many awards, most notably the 1992 Nobel Prize in chemistry. Marcus was born in Montreal. He received a B.Sc. degree in chemistry from McGill University in 1943, and a Ph.D. degree from the same institution in 1946. After doing postdoctoral research at the National Research Council of Canada and at the University of North Carolina, Chapel Hill, he became a professor at the Polytechnic Institute of Brooklyn from 1951 to 1964 and at the University of Illinois from 1964 to 1978, when he was named the Arthur Amos Noyes Professor of Chemistry at California Institute of Technology. His seminal contributions to the realms of electron transfer theory and intramolecular dynamics continue to earn him honors, including the 1997 ACS Award in Theoretical Chemistry. 

Shalashilin and Thompson [46-48] developed a method based on classical diffusion theory for calculating unimolecular reaction rates in the IVR-limited regime. This method, which they referred to as intramolecular dynamics diffusion theory (IDDT) requires the calculation of short-time ( fs) classical trajectories to determine the rate of energy transfer from the bath modes of the molecule to the reaction coordinate modes. This method, in conjunction with MCVTST, spans the full energy range from the statistical to the dynamical limits. It in essence provides a means of accurately... 

Goodyear G, Stratt RM. The short-time intramolecular dynamics of solutes in liquids. I. An instantaneous-normal-mode theory for friction. J Chem Phys 1996 105 10050-10071. 

Introduction to Group Theory for Non-Rigid Molecules 10.3 Intramolecular Dynamics... 

Guo. Y.. Shalashilin. D. V.. Krouse. J. A. and Thompson. D. L.(1999) Intramolecular dynamics diffusion theory approach to complex unimolecular reactions, J. Chem. Phys. 110, 5521-5525. 

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