0
2013
Impact Factor

Makrina Agaoglou

Publications:

Haigh D., Katsanikas M., Agaoglou M., Wiggins S.
The Time Evolution of the Trajectories After the Selectivity in a Symmetric Potential Energy Surface with a Post-transition-state Bifurcation
2021, vol. 26, no. 6, pp.  763-774
Abstract
Selectivity is an important phenomenon in chemical reaction dynamics. This can be quantified by the branching ratio of the trajectories that visit one or the other well to the total number of trajectories in a system with a potential with two sequential index-1 saddles and two wells (top well and bottom well). In our case, the relative branching ratio is 1:1 because of the symmetry of our potential energy surface. The mechanisms of transport and the behavior of the trajectories in this kind of systems have been studied recently. In this paper we study the time evolution after the selectivity as energy varies using periodic orbit dividing surfaces. We investigate what happens after the first visit of a trajectory to the region of the top or the bottom well for different values of energy. We answer the natural question: What is the destiny of these trajectories?
Keywords: phase space structure, dividing surfaces, chemical physics, periodic orbits, homoclinic and heteroclinic orbits
Citation: Haigh D., Katsanikas M., Agaoglou M., Wiggins S.,  The Time Evolution of the Trajectories After the Selectivity in a Symmetric Potential Energy Surface with a Post-transition-state Bifurcation, Regular and Chaotic Dynamics, 2021, vol. 26, no. 6, pp. 763-774
DOI:10.1134/S1560354721060137
Crossley R., Agaoglou M., Katsanikas M., Wiggins S.
From Poincaré Maps to Lagrangian Descriptors: The Case of the Valley Ridge Inflection Point Potential
2021, vol. 26, no. 2, pp.  147-164
Abstract
In this paper we compare the method of Lagrangian descriptors with the classical method of Poincaré maps for revealing the phase space structure of two-degree-of-freedom Hamiltonian systems. The comparison is carried out by considering the dynamics of a twodegree- of-freedom system having a valley ridge inflection point (VRI) potential energy surface. VRI potential energy surfaces have four critical points: a high energy saddle and a lower energy saddle separating two wells. In between the two saddle points is a valley ridge inflection point that is the point where the potential energy surface geometry changes from a valley to a ridge. The region between the two saddles forms a reaction channel and the dynamical issue of interest is how trajectories cross the high energy saddle, evolve towards the lower energy saddle, and select a particular well to enter. Lagrangian descriptors and Poincaré maps are compared for their ability to determine the phase space structures that govern this dynamical process.
Keywords: phase space structure, periodic orbits, stable and unstable manifolds, homoclinic and heteroclinic orbits, Poincar´e maps, Lagrangian descriptors
Citation: Crossley R., Agaoglou M., Katsanikas M., Wiggins S.,  From Poincaré Maps to Lagrangian Descriptors: The Case of the Valley Ridge Inflection Point Potential, Regular and Chaotic Dynamics, 2021, vol. 26, no. 2, pp. 147-164
DOI:10.1134/S1560354721020040

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