Chaos gated tunneling drives molecular reactivity in astrophysical environments

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 H₃⁺ and the proton-bound cluster H₅⁺ as representative model systems relevant to Jovian atmospheres, we demonstrate that the Transition State (TS) acts as a dynamical bottleneck where quantum chaos is notably suppressed ( r ≈ 0.36 ), 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.