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Mind the GAP: Quantifying the Breakdown of the Linear Vibronic Coupling Hamiltonian

Lookup NU author(s): Dr Julien EngORCiD, Professor Thomas Penfold

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).

Abstract

Excited state dynamics play a critical role across a broad range of scientific fields. Importantly, the highly non-equilibrium nature of the states generated by photoexcitation means that excited state simulations should usually include an accurate description of the coupled electronic-nuclear motion, which often requires solving the time-dependent Schrödinger equation (TDSE). One of the biggest challenges for these simulations is the requirement to calculate the PES over which the nuclei evolve. An effective approach for addressing this challenge is to use the approximate linear vibronic coupling (LVC) Hamiltonian, which enables a model potential to be parameterised using relatively few quantum chemistry calculations. However, this approach is only valid provided there are no large amplitude motions in the excited state dynamics. In this paper we introduce and deploy a metric, the Global Anharmonicity Parameter (GAP), which can used to assess the accuracy of an LVC potential. Following its derivation, we illustrate its utility by applying it to three molecules exhibiting different rigidity in their excited states.

Publication metadata

Author(s): Eng J, Penfold TJ

Publication type: Article

Publication status: Published

Journal: Physical Chemistry Chemical Physics

Year: 2023

Volume: 25

Issue: 10

Pages: 7195-7204

Online publication date: 09/02/2023

Acceptance date: 08/02/2023

Date deposited: 09/02/2023

ISSN (print): 1463-9076

ISSN (electronic): 1463-9084

Publisher: Royal Society of Chemistry

URL: https://doi.org/10.1039/D2CP05576G

DOI: 10.1039/D2CP05576G

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