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Transition state theory with colored noise

Transition state theory with colored noise

Datum: 20. Juni 2017 13:15

Ort: NWZ II, Raum 4.331, Pfaffenwaldring 57, Stuttgart-Vaihingen

Transition state theory with colored noise
Fabio Revuelta, Universidad politécnica de Madrid

The usual identification of reactive trajectories for the calculation of reaction rates requires very time-consuming simulations due to the ingent number of particles that form the bath that surrounds the system under study. Thus, several different methods have been developed to speed up these extremely demanding calculations, while adequately describing the reaction process. Transition State Theory (TST) [1] is certainly one of the most successful methods for this purpose. TST is able to (i) identify reactive trajectories, and (ii) compute reaction rates. This theory is based on the study of the transition state or activated complex that is formed when the reaction takes places, evolving from the reactants to the products. The transition state is an intermediate configuration that lives at the top of the energetic barrier that separates these two states, and acts as a bottleneck for chemical reactivity.

In this talk we will present a time-dependent version of TST based on the identification of the phase space objects that act as separatrices for chemical reactivity. These structures, which are invariant manifolds, are attached to the transition state trajectory, a very particular trajectory that remains randomly moving or jiggling in the vicinity of the barrier top for all times. As we will demonstrate, our procedure is able to identify reactive trajectories uniquely and compute reaction rates without any numerical simulation. The accuracy of our calculations is demonstrated by adequately computing rates in several model potentials [2], as well as in a realistic molecular system, the LiNC/LiCN isomerizing molecule [3], described using a Generalized Langevin Equation.

[1] B. C. Garrett, and D. G. Truhlar, in ”Theory and Applications of Computational Chemistry: The First Forty Years”, edited by C. E. Dykstra, G. Frenking, K. S. Kim, and G. E. Scuseria (Elsevier, 2005) Chap. 5, pp. 67–87.
[2] T. Bartsch, F. Revuelta, R. M. Benito, and F. Borondo, “Rate calculation with correlated noise”, arXiv:1608.05397.
[3] F. Revuelta, T. Bartsch, P. L. Garcia-Muller, R. Hernandez, R. M. Benito, and F. Borondo, Phys. Rev. E 93, 062304 (2016).

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