  The processing and material properties of commercial organic semiconductors,
for e.g. fullerenes is largely controlled by their precise arrangements,
specially intermolecular symmetries, distances and orientations, more
specifically, molecular polarisabilities. These supramolecular parameters
heavily influence their electronic structure, thereby determining molecular
photophysics and therefore dictating their usability as n-type semiconductors.
In this article we evaluate van der Waals potentials of a fullerene dimer model
system using two approaches: a) Density Functional Theory and, b) Macroscopic
Quantum Electrodynamics, which is particularly suited for describing long-range
van der Waals interactions. Essentially, we determine and explain the model
symmetry, distance and rotational dependencies on binding energies and spectral
changes. The resultant spectral tuning is compared using both methods showing
correspondence within the constraints placed by the different model
assumptions. We envision that the application of macroscopic methods and
structure/property relationships laid forward in this article will find use in
fundamental supramolecular electronics.
