Issue 23, 2019

Non-adiabatic molecular dynamics investigation of the size dependence of the electronic relaxation in polyacenes

Abstract

The Tully's fewest switches surface hopping algorithm is implemented within the framework of the time-dependent density functional based tight binding method (TD-DFTB) to simulate the energy relaxation following absorption of a UV photon by polycyclic aromatic hydrocarbons (PAHs). This approach is used to study the size effect on the ultrafast dynamics in excited states for a special class of PAH species called polyacenes. We determine the dynamical relaxation times and discuss the underlying mechanisms. Our results show that there is a striking alternation in decay times of the brightest singlet state for neutral polyacenes with 3 to 6 aromatic cycles. The alternation corresponds to an order-of-magnitude variation between roughly 10 and 100 fs and is correlated with a qualitatively similar alternation of energy gaps between the brightest state and the state lying just below in energy.

Graphical abstract: Non-adiabatic molecular dynamics investigation of the size dependence of the electronic relaxation in polyacenes

Supplementary files

Article information

Article type
Paper
Submitted
30 Jan 2019
Accepted
17 May 2019
First published
17 May 2019

Phys. Chem. Chem. Phys., 2019,21, 12139-12149

Non-adiabatic molecular dynamics investigation of the size dependence of the electronic relaxation in polyacenes

E. Posenitskiy, M. Rapacioli, B. Lepetit, D. Lemoine and F. Spiegelman, Phys. Chem. Chem. Phys., 2019, 21, 12139 DOI: 10.1039/C9CP00603F

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