Nonadiabatic Electronic Energy Transfer in the Chemical Oxygen–Iodine Laser: Powered by Derivative Coupling or Spin–Orbit Coupling?

Abstract

Derivative couplings near a conical intersection and spin–orbit couplings between different spin states are known to facilitate nonadiabatic transitions in molecular systems. Here, we investigate a prototypical electronic energy transfer process, I­(2 P 3/2) + O2(a 1Δ g ) → I­(2 P 1/2) + O2(X 3Σ g –), which is of great importance for the chemical oxygen–iodine laser. To understand the nonadiabatic dynamics, this multistate process is investigated in full dimensionality with quantum wave packets using diabatic potential energy surfaces coupled by both derivative and spin–orbit couplings, all determined from first principles. A near quantitative agreement with structural, energetic, and kinetic measurements is achieved. Detailed analyses suggest that the nonadiabatic dynamics is largely controlled by derivative coupling near conical intersections, which leads to a small effective barrier and hence a slightly positive temperature dependence of the rate coefficient. The new results should extend our understanding of energy transfer, provide a quantitative basis for numerical simulations of the chemical oxygen–iodine laser, and have important implications in other electronic energy transfer processes.

Full-dimensional quantum stereodynamics of the non-adiabatic quenching of OH(A2Σ+) by H2

“…While ultrafast non-adiabatic transitions near a CI have been extensively studied in photochemistry 2 – 8 and non-reactive collisions 9 – 11 , fewer studies on non-Born–Oppenheimer effects exist for bimolecular reactions 12 . Existing first-principles theories of non-adiabatic reaction dynamics mostly deal with open-shell atoms, focusing on geometric phase effects 13 – 15 or spin–orbit excited electronic states 16 – 21 . Here we extend the full-dimensional quantum description to the quenching of an electronically excited molecule: …”

Neural Network Based Quasi-diabatic Representation for S0 and S1 States of Formaldehyde

“…Extensive theoretical studies of IC processes via conical intersections have been reported; even for some photochemical systems, quantitative dynamics results that agree with experimental results have been obtained. , However, fewer dynamic studies of ISC that go beyond qualitative rules have been reported. − One of the challenges in the accurate studies of ISC is the electronic structure calculations of excited states. In order to describe a photochemical system globally, multireference (MR) methods are mandatory, which can be prohibitively expensive for medium and large systems .…”

Internal conversion and intersystem crossing dynamics based on coupled potential energy surfaces with full geometry-dependent spin–orbit and derivative couplings. Nonadiabatic photodissociation dynamics of NH3(A) leading to the NH(X3Σ−, a1Δ) + H2 channel

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