On the time-dependent calculation of angular averaged vibronic absorption spectra with an application to molecular aggregates
Chemical Physics, (2017)Electrons and nuclei in motion - correlation and dynamics in molecules (on the occasion of the 70th birthday of Lorenz S. Cederbaum).DOI: 10.1016/j.chemphys.2016.08.019
Abstract
Abstract We introduce an efficient method to determine angular averaged absorption spectra for cases where electronic transitions take place to a manifold of N coupled excited states. The approach rests on the calculation of time-dependent auto-correlation functions which, upon Fourier-transform yield the spectrum. Assuming the Condon-approximation, it is shown that three wave-packet propagations are sufficient to calculate the spectrum. This is in contrast to a direct approach where it is necessary to perform N propagations to arrive at \N2\ cross-correlation functions. The reduction in computation time is of importance for larger molecular aggregates where the number N is determined by the aggregate size. We provide an example by determining spectra for macrocyclic dyes in different dipole-geometries.