Detection of Dynamical Matching in a Caldera Hamiltonian System using Lagrangian Descriptors

TL;DR

This paper uses Lagrangian descriptors to analyze phase space structures in a Caldera Hamiltonian system, revealing how heteroclinic connections influence the occurrence of dynamical matching and enabling prediction of this behavior.

Contribution

It introduces a novel application of Lagrangian descriptors to identify phase space mechanisms behind dynamical matching in Caldera systems, improving prediction accuracy.

Findings

Heteroclinic connections prevent dynamical matching.

Absence of heteroclinic connections allows dynamical matching.

Critical stretching parameter for dynamical matching identified.

Abstract

The goal of this paper is to apply the method of Lagrangian descriptors to reveal the phase space mechanism by which a Caldera-type potential energy surface (PES) exhibits the dynamical matching phenomenon. Using this technique, we can easily establish that the non-existence of dynamical matching is a consequence of heteroclinic connections between the unstable manifolds of the unstable periodic orbits (UPOs) of the upper index-1 saddles (entrance channels to the Caldera) and the stable manifolds of the family of UPOs of the central minimum of the Caldera, resulting in the temporary trapping of trajectories. Moreover, dynamical matching will occur when there is no heteroclinic connection, which allows trajectories to enter and exit the Caldera without interacting with the shallow region of the central minimum. Knowledge of this phase space mechanism is relevant because it allows us to effectively predict the existence, and non-existence, of dynamical matching. In this work we explore a stretched Caldera potential by means of Lagrangian descriptors, allowing us to accurately compute the critical value for the stretching parameter for which dynamical matching behavior occurs in the system. This approach is shown to provide a tremendous advantage for exploring this mechanism in comparison to other methods from nonlinear dynamics that use phase space dividing surfaces.