How Van der Waals Interactions Influence the Absorption Spectra of Pheophorbide a Complexes: A Mixed Quantum-Classical Study.
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 a (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.
Institut für Chemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25,D-14476 Potsdam (Germany). megow@uni-potsdam.de.
Jörg
J
Megow
dispersion; electrostatic interactions; mixed quantum-classical methodology; optical spectra; supramolecular chemistry