Effect of interatomic potentials on modeling the nanostructure of amorphous carbon by liquid quenching method

Abstract

Extending from our previous work (Li et al., 2013), eight different carbon interatomic potentials, Tersoff1989, Tersoff1994, REBO-Ⅱ, AIREBO, ReaxFF, COMB3, REBO-II + S and Tersoff + S, are applied to conduct a comparative study on the nanostructure of amorphous carbon films. The amorphous carbon films at different density are modeled by LAMMPS with liquid quenching method. The atomic structure of a-C film is analyzed in terms of coordination number, radial distribution function, the bond angle distribution and Voronoi polyhedra. The effect of interatomic potentials on atomic cohesive energy and time consumption are analyzed and compared. No two potentials model the a-C film with the same atomic structure. The a-C films modeled by REBO-II + S and Tersoff + S potentials are consistent with experimental data and DFT results at density from 2.2 to 3.2 g/cm3. High sp3 carbon rate is modeled by Tersoff1994, and high sp2 carbon rate is modeled by REBO-Ⅱ and AIREBO. Lot of three-atom-rings are found when COMB3 is used. The sp3 and sp2 carbon rate are similar modeled by Tersoff1989 and ReaxFF. But there are sp1 carbon chains in a-C films modeled by ReaxFF at low density. Those results are conducive for researchers to evaluate and choose of interatomic potentials.