We propose and test an extension of the energy grained master equation (EGME) for treating nonadiabatic (NA) hopping between different potential energy surfaces, which enables us to model the competition between stepwise collisional relaxation and kinetic processes which transfer population between different electronic states of the same spin symmetry. By incorporating Zhu-Nakamura theory into the EGME, we are able to treat nonadiabatic passages beyond the simple Landau-Zener approximation, along with corresponding treatments of zero-point energy and tunnelling probability. To evaluate the performance of this NA-EGME approach, we carried out detailed studies of the UV photodynamics of the volatile organic compound C6-hydroperoxyaldehyde (C6-HPALD) using on-the-fly ab initio molecular dynamics and trajectory surface hopping. For this multi-chromophore molecule, we show that the EGME is able to capture important aspects of the dynamics, including kinetic timescales, and diabatic trapping. Such an approach provides a promising and efficient strategy for treating the long-time dynamics of photoexcited molecules in regimes which are difficult to capture using atomistic on-the-fly molecular dynamics.
Bibliographical noteFunding Information:
D.R.G. acknowledges funding from the Royal Society as a University Research Fellow. R.J.S. is supported by EPSRC Programme grant no. EP/P021123/1. D.S. acknowledges Ph.D. studentship support from the EPSRC Centre for Doctoral Training in Theory and Modelling in Chemical Sciences (EP/L015722/1). This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreements 803718 and 701355—Projects SINDAM and NAMDIA). The authors thank Todd Martínez for useful discussions at various stages of this project.
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