A modified Tersoff potential for pure and hydrogenated diamond-like carbon

The structure of diamond-like carbon (DLC) features an amorphous topology with a high fraction of sp3 bonds, which increases with density and reaches over 80% at 3.0 g/cm3. To perform large-scale simulations of DLC using interatomic potentials one should be able to generate this structure using a melting and quenching procedure. In the present work, we evaluate the accuracy of different bond order interatomic potentials developed for carbon and hydrocarbons to describe the properties of DLC, in particular its structure. The potentials include the reactive empirical bond order (REBO) and variants of the Tersoff potentials (standard, ZBL, extended cutoff). Results indicate that Tersoff potential with extended cutoff of 2.45 Å is the most accurate in reproducing the experimental structure and mechanical properties of DLC and DLCH (hydrogenated diamond-like carbon). The calculated sp3 fraction as a function of density, pair correlation functions, and Young’s modulus as a function of density show excellent agreement with experimental data. Our findings suggest that the Tersoff potential with extended cutoff is a reliable interatomic potential for large-scale atomistic simulations of both DLC and DLCH.

► We assess the quality of DLC models generated using different Tersoff potentials.
► Tersoff potential with extended cutoff at 2.45 Å correctly predicts sp3 content vs. density.
► The modified Tersoff potential also describe well DLC and DLCH mechanical properties.