MELTING OF A REPULSIVE SCREENED COULOMB SYSTEM IN 2 DIMENSIONS - EFFECT OF
CORRUGATION
Seong-HS, Mahanti-SD, Sen-S, Cagin-T, Physical Review
B 46, 8748-8755(1992)
ABSTRACT
By use of constant energy molecular dynamics simulations, we have
investigated the melting and freezing transitions in a two-dimensional
system consisting of a constant density of classical particles interacting
with a repulsive screened Coulomb (Yukawa) potential. In particular, we
have investigated the role of an incommensurate substrate corrugation
potential of sixfold symmetry on these transitions by probing the
temperature dependence of the bond orientational order parameter (psi6) and
the corresponding susceptibility (chi6). Other physical quantities such as
energy, diffusion constant, and the density of local topological defects
have been monitored through the transition region. In the absence of a
corrugation potential the system shows a sharp melting transition. In the
presence of a corrugation potential the transition temperature increases
and the transition becomes smoother. In contrast to the corrugation-free
case we find a broad peak in chi6 above the transition temperature. We
interpret this behavior in terms of the melting of a domain-wall solid. The
detailed nature of this smooth transition depends on the degree of
incommensurability. Relevance of these results to stage-2 graphite
intercalation compounds is discussed.