The Theory Group of R. Fink investigates the structure, charge- and energy-transport properties of molecular aggregates, nanoparticles, and crystals. Currently the major topics are (1) description of exciton transport properties in organic molecular crystals, (2) energetically favourable arrangements of organic dyes, (3) the charge transport in organic materials, (4) the dependence of the absorption spectra of organic solids on the arrangement of the dye molecules, and (5 ) a theoretical description of core electron spectra.

Collaborations exist with the groups Meixner/Zhang (characterization of the ground and excited states of dye molecules on solid surfaces), Chassé (Structural and core electron spectroscopic characterization of molecules on surfaces), Brecht (energy transfer and charge generation), and Schreiber (structure of molecules on surfaces).