Optimizing the structure of acene clusters.

We present a study of the potential energy surface of anthracene, tetracene, and pentacene clusters with up to 30 molecules. We have applied the basin-hopping Monte Carlo algorithm to clusters of acene molecules in order to find their lowest energy states. The acene molecules are described by the polymer-consistent force field-interface force field. We present the structures with the lowest observed energy, and we discuss the relative stability and accessibility of structures corresponding to local energy minima.