We report density-functional based molecular-dynamics simulations, which show that, with increasing pressure, liquid carbon undergoes a gradual transformation from a liquid with local threefold coordination to a “diamondlike” liquid. We demonstrate that this unusual structural change is well reproduced by an empirical bond-order potential with isotropic long-range interactions, supplemented by torsional terms. In contrast, state-of-the-art short-range bond-order potentials do not reproduce this diamond structure. This suggests that a correct description of long-range interactions is crucial for a unified description of the solid and liquid phases of carbon.

• Received 31 October 2003

DOI:https://doi.org/10.1103/PhysRevB.69.100101