Steps on
surfaces in modeling crystal growth
Deij, M. A., Cuppen, H. M., Meekes, H., Vlieg, E.
CRYSTAL GROWTH & DESIGN 7 (10): 1936-1942 OCT 2007
Abstract: When modeling
crystal growth and crystal morphology, steps on surfaces are important
for the correct description of the phenomena taking place. Morphology
prediction, however, has been dominated by the Hartman-Perdok theory of
periodic bond chains (PBCs), connected nets, and attachment energy,
where steps are ignored. In this paper, using three model systems we
show that the Hartman-Perdok theory breaks down for complex connected
net topologies, in terms of connected nets having a roughening
temperature equal to zero. A two-fold solution to understanding this
anomalous behavior is presented. First of all, looking at step
structures that can form on a connected net orientation and calculating
the energies associated with them lead to a better understanding of the
roughening behavior. A recently developed algorithm for that, called
STEPLIFT, is introduced in the accompanying article in this issue
(Cryst. Growth Des. 2007, 7, 1949-1957). Second, performing atomistic
Monte Carlo simulations for selected orientations allows for the
detailed simulation of the growth process as a function of the driving
force. The presence or absence of a nucleation barrier can thus be
tested. These two complementary methods give new insights in the
possible growth behavior and roughening of complex organic materials
and are expected to lead to new methods for modeling crystal growth,
crystal surfaces, and crystal morphology.