# Blog de la Biblioteca de Matemàtiques i Informàtica # SIMBa: Influence of a laser pulse on the isomerization dynamics of the LiNC/LiCN molecular system El proper divendres, 31 de maig, se celebrarà una nova sessió del Seminari Informal de Matemàtiques de Barcelona (SIMBa).

Speaker: Henar Hernández Mendiola

Data: divendres 31 de maig de 2013
Hora: 15:15, coffee break; 15:30, inici
Lloc: Aula IMUB (al terrat), Facultat de Matemàtiques de la Universitat de Barcelona.

Títol: Influence of a laser pulse on the isomerization dynamics of the LiNC/LiCN molecular system
Resum: The Transition Sate Theory allows us to obtain kinetic information about molecular systems without knowing the whole Potential Energy Surface. It is necessary to obtain a dividing surface on the phase space. The equator of the dividing surface corresponds to the so called “activated complex”. Once it is known it makes possible to obtain the gap time distributions, the reactive density of states, or the reactive flux across it and so, to calculate reaction rates.
Such a dividing surface can be calculated even if the Hamiltonian function depends on time. That fact enables us to include laser-pulse perturbations , and so to study its effect on the dynamics and kinetics of molecular systems. We study the isomerization process for the molecular system LiNC/LiCN. A general way to write the Hamiltonian function is: $H(R,\theta,p_R,p_\theta,t) = H_0(R,\theta,p_R,p_\theta) + R\xi(t)\cos\alpha$ where $H_0(R,\theta,p_R,p_\theta)$ is the Hamiltonian of the aisolated system, $R,\theta$ are the Jacobi coordinates, $p_R,p_\theta$ are the conjugated momenta, $\alpha$ is the angle between the C-N and $\xi(t)$ the pulse and is the function that simulates the electromagnetic pulse. The mathematical equation that describes the pulse has been taken from Ref. 1. It depends on some parameters such as the period of the perturbation, the amplitude or the frecuency. The main goal of this project is to study the influence of that parameters on the dynamical geometric objects near the dividing surface (transition state, normaly hiperbolic invariant manifold and its stable and unstable manifolds) and on the kinetic data mentioned before.

 S. Kawai, A. D. Bandrauk, C. Jaffé, T. Bartsch, J. Palacián, T. Uzer, Transition state theory for laser-driven reactions. J. Chem. Phys. 126, 164306 (2007).

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