Chaos Gated Tunneling Drives Molecular Reactivity in Astrophysical Environments

TL;DR

This paper develops a chaos-diagnostic framework combining electronic structure theory, AGP, and RMT to understand how vibrational dynamics influence tunneling and reactivity in astrochemical ion-molecule reactions.

Contribution

It introduces a new chaos-based diagnostic method to identify vibrationally gated pathways affecting reaction rates in ultracold astrophysical environments.

Findings

Transition states suppress chaos, enhancing tunneling in model systems.

Fragility index quantifies vibrational mode reintroduction of chaos.

Framework offers a data-driven approach to refine astrochemical reaction models.

Abstract

Accurate modeling of ion-molecule reaction networks is essential for understanding the chemical evolution of planetary ionospheres, particularly for giant planets where proton-transfer chains drive atmospheric composition. However, predicting reaction rates in these ultracold environments remains a challenge due to the non-trivial interplay between vibrational dynamics and quantum tunneling. In this work we present a chaos-diagnostic framework that integrates multireference electronic structure theory, Adiabatic Gauge Potentials (AGP), and Random Matrix Theory (RMT) to characterize the microscopic dynamics of proton transport. Using the formation of H+3 and the proton-bound cluster H+5 as representative model systems relevant to Jovian atmospheres, we demonstrate that the transition state acts as a dynamical bottleneck where quantum chaos is notably suppressed, effectively enhancing tunneling probabilities. We introduce a fragility index based on the AGP slope to quantify how specific vibrational modes reintroduce chaos and suppress reactivity. This diagnostic approach offers a generalizable, data-driven metric for identifying vibrationally gated pathways in complex astrochemical networks, providing a theoretical basis for refining kinetic models of planetary and interstellar plasmas