Equilibrium and Growth Morphology of Oligoacenes: Periodic Bond Chains Analysis of Naphthalene, Anthracene, and Pentacene Crystals

The athermal equilibrium and growth crystal shapes of a series of oligoacenes, namely, naphthalene, anthracene, and pentacene, were simulated, in a vacuum, by using three different sets of empirical potentials (UNI, UFF, and MM3 force fields). By applying the Hartman-Perdok method of the periodic bond chains (PBC), the surface profiles were obtained, providing the specific surface and attachment energy values, both for ideal and relaxed surfaces. Very good agreement among the three force fields employed was observed. From calculations, it ensues that surface relaxation only weakly affects surface and, even more, attachment energies of these semiconductor molecular crystals. It is noteworthy to point out that both equilibrium and growth shapes of these crystals are quite similar when concerning phases belonging to the same point group.