A general non-adiabatic quantum instanton approximation

Abstract

We present a general quantum instanton approach to calculating reaction rates for systems with two electronic states and arbitrary values of the electronic coupling. This new approach, which we call the non-adiabatic quantum instanton (NAQI) approximation, reduces to Wolynes theory in the golden rule limit and to a recently proposed projected quantum instanton (PQI) method in the adiabatic limit. As in both of these earlier theories, the NAQI approach is based on making a saddle point approximation to the time integral of a reactive flux autocorrelation function, although with a generalised definition of the projection operator onto the product states. We illustrate the accuracy of the approach by comparison with exact rates for one dimensional scattering problems and discuss its applicability to more complex reactions.

9 pages, 6 figures

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Cited by in corpus (7)

• Nonadiabatic instanton rate theory beyond the golden-rule limit
• Dissipative Tunneling Rates through the Incorporation of First-Principles Electronic Friction in Instanton Rate Theory I: Theory
• An improved path-integral method for golden-rule rates
• Semiclassical instanton theory for reaction rates at any temperature: How a rigorous real-time derivation solves the crossover temperature problem
• Coupling electrons and vibrations in molecular quantum chemistry
• Nonadiabatic transition paths from quantum jump trajectories
• Extending non-adiabatic rate theory to strong electronic couplings in the Marcus inverted regime