  Assuming a delta pulse excitation, quantum wavepackets are propagated on the
excited state manifold in the energy range from 3.4-5.0 eV for coronene and
2.4-3.5 eV for circumcoronene to study the time evolution of the states as well
as their lifetimes. The full-dimensional (102 and 210 degrees of freedom for
coronene and circumcoronene respectively) non-adiabatic dynamics simulated with
the ML-MCTDH method on twelve coupled singlet electronic states show that the
different absorption spectra are only due to electronic delocalisation effects
that change the excited state energies, but the structural dynamics in both
compounds are identical. Breathing and tilting motions drive the decay dynamics
of the electronic states away from the Frank-Condon region independently of the
size of the aromatic system. This promising result allows the use of coronene
as a model system for the dynamics of larger polycyclic aromatic hydrocarbons
(PAHs) and graphene one dimensional sheets or nanoflakes.
