Surface energetics and growth of pentacene

First-principles pseudopotential density-functional calculations for pentacene and anthracene are used to obtain atomic structures, cohesive energies, and surface energies for the low index surfaces. For pentacene, calculations predict that the (001) surface has a much lower surface energy than the other surfaces. From the first-principles results a general model of the intermolecular bonding is developed. This model may be employed to estimate the surface energies and cohesive energy for any polyacene crystal. Implications of the present results for understanding the temperature dependence of the growth morphology of pentacene are discussed.