Description:
<jats:title>Abstract</jats:title><jats:p>The computation of dispersive site energy shifts due to van der Waals interaction (London dispersion forces) was combined with mixed quantum–classical methodology to calculate the linear optical absorption spectra of large pheophorbide <jats:italic>a</jats:italic> (Pheo) dendrimers. The computed spectra agreed very well with the measurements considering three characteristic optical features occurring with increasing aggregate size: a strong line broadening, a redshift, and a low‐energy shoulder. The improved mixed quantum–classical methodology is considered a powerful tool in investigating molecular aggregates.</jats:p>