RIM Laboratory of Solid State Chemistry, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands
Institute for Theoretical Physics, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands
Department of Physics, University of Washington, Seattle, Washington 98195
The (011) surface of the naphthalene crystal structure is described by a simple restricted solid-on-solid model that is
applicable to a wide range of organic crystals. Despite the absence of next-nearest-neighbor bonds, the phase diagram of the
model exhibits, besides flat and rough phases, a disordered flat phase. Monte Carlo simulations confirm this phase diagram.
The presence of a disordered flat phase explains the sudden disappearance of the (011) facet in experimental growth shapes
of naphthalene. The type of step-free energy associated with surface tilt decreases rapidly, at preroughening transitions. This
leads to a rapid decrease in the nucleation barrier, which results in a sudden enhanced growth rate and, under certain
conditions, to the complete disappearance of this facet in growth shapes.