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Nonadiabatic dynamics of cycloparaphenylenes with TD-DFTB surface hopping

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posted on 16.03.2018 by Ljiljana Stojanovic, Saadullah G. Aziz, Rifaat H. Hilal, Felix Plasser, Thomas A. Niehaus, Mario Barbatti
© 2017 American Chemical Society. We implemented a version of the decoherence-corrected fewest switches surface hopping based on linear-response time-dependent density functional tight binding (TD-DFTB), enhanced by transition density analysis. The method has been tested for the gas-phase relaxation dynamics of two cycloparaphenylene molecules, [8]CPP and [10] CPP, explaining some important features of their nonadiabatic dynamics, such as the origin of their long fluorescence lifetimes (related to the slow radiative emission from the S 1 state) and the trend of increasing the fluorescence rate with the molecular size (related to an increase in the S 1 -S 0 energy gaps and oscillator strengths in the larger molecule). The quality of the TD-DFTB electronic structure information was assessed through four quantities: excitation energies; charge-transfer (CT) numbers, which estimate the charge transfer character of states; participation ratio (PR), which describes delocalization of electronic density; and participation ratio of natural transition orbitals (PRNTO), which describes the multiconfigurational character of states. These quantities were computed during dynamics and recomputed for the same geometries with the higher-level long-range-corrected TD-LC-DFTB and a lower-level single-determinant approximation for the excited states, SD-(LC)-DFTB. Taking TD-LC-DFTB as the standard, TD-DFTB underestimates the excitation energies by ~0.5 eV and overestimates CT and PR. SD-DFTB underestimates excitation energies and overestimates CT to the same extent that TD-DFTB does, but it predicts reasonable PR distributions. SD-LC-DFTB leads to an extreme overestimation of the excitation energies by ~3 eV, overestimates the charge transfer character of the state, but predicts the PR values very close to those obtained with TD-LC-DFTB.

Funding

This Project was funded by the Deanship of Scientific Research (DSR) King Abdulaziz University, Jeddah, under grant no. 43-130-35-RG. The authors, therefore, acknowledge DSR support for Scientific Research. MB and LS work was supported by Excellence Initiative of Aix- Marseille University (A*MIDEX) and the project Equip@Meso (ANR-10-EQPX-29-01), both funded by the French Government “Investissements d’Avenir” program. MB also acknowledges funding from HPC resources from GENCI-CINES Grant 2017-A0010810012).

History

School

  • Science

Department

  • Chemistry

Published in

Journal of Chemical Theory and Computation

Volume

13

Issue

12

Pages

5846 - 5860

Citation

STOJANOVIC, L. ...et al., 2017. Nonadiabatic dynamics of cycloparaphenylenes with TD-DFTB surface hopping. Journal of Chemical Theory and Computation, 13(12), pp. 5846-5860.

Publisher

© American Chemical Society (ACS)

Version

AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2017-11-15

Notes

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Chemical Theory and Computation, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.jctc.7b01000.

ISSN

1549-9618

eISSN

1549-9626

Language

en

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