Nonadiabatic excited-state dynamics and energy gradients in the framework of FMO-LC-TDDFTB

Richard Einsele; Roland Mitrić

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arXiv · 2404.14174

Nonadiabatic excited-state dynamics and energy gradients in the framework of FMO-LC-TDDFTB

Richard Einsele·Roland Mitrić

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Abstract

We introduce a novel methodology for simulating the excited-state dynamics of extensive molecular aggregates in the framework of the long-range corrected time-dependent density-functional tight-binding fragment molecular orbital method (FMO-LC-TDDFTB) combined with the mean-field Ehrenfest method. The electronic structure of the system is described in a quasi-diabatic basis composed of locally excited and charge-transfer states of all fragments. In order to carry out nonadiabatic molecular dynamics simulatios, we derive and implement the excited-state gradients of the locally excited and charge-transfer states. Subsequently, the accuracy of the analytical excited-state gradients is evaluated. The applicability to the simulation of exciton transport in organic semiconductors is illustrated on a large cluster of anthracene molecules. Additionally, nonadiabatic molecular dynamics simulations of a model system of benzothieno-benzothiophene molecules highlight the methods utility in studying charge-transfer dynamics in organic materials. Our new methodology will facilitate the investigation of excitonic transfer in extensive biological systems, nanomaterials and other complex molecular systems consisting of thousands of atoms.

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Richard Einsele, Roland Mitrić. 2024-04-22. Nonadiabatic excited-state dynamics and energy gradients in the framework of FMO-LC-TDDFTB. https://arxiv.org/abs/2404.14174

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