Improved long-range reactive
bond-order potential for carbon. II. Molecular simulation of liquid
carbon
Luca M. Ghiringhelli, Jan H. Los, A. Fasolino, and Evert Jan Meijer
Abstract
Using the recently developed state-of-the-art empirical bond-order
potential (LCBOPII), presented in the companion paper [Los et al.,
Phys. Rev. B 72, 214102 (2005)], we study liquid carbon by Monte Carlo
simulation. We determined the equation-of-state and local structure
over a wide range of temperatures (4000–15 000 K) and
pressures (up to 300 GPa). Comparison of the equation-of-state
and local structure along the 6000 K isotherm with benchmark ab
initio molecular dynamics data shows that LCBOPII provides accurate
predictions. The local coordination varies gradually from mixed two-
and three-fold, via dominantly threefold, to mainly fourfold with
increasing temperature and pressure. This provides evidence that there
is no liquid-liquid phase separation as confirmed by the regular
behavior of the pressure-density relations along the isotherms in the
range of 5000–15 000 K. We provide an accurate fit of the
pressure-temperature-density equation-of-state that may serve as a
reference for future studies of liquid carbon.