Recent developments and simulations utilizing bond-order potentials

Abstract

Bond-order potentials (BOPs) have been used successfully in simulations of a wide range of processes. A brief overview of bond-order potentials is provided which focuses on the reactive empirical bond-order (REBO) potential for hydrocarbons (Brenner et al 2002 J. Phys.: Condens. Matter 14 783) and the large number of useful potentials it has spawned. Two specific extensions of the REBO potential that make use of its formalism are discussed. First, the 2B-SiCH potential (Schall and Harrison 2013 J. Phys. Chem. C 117 1323) makes the appropriate changes to the hydrocarbon REBO potential so that three atom types, Si, C, and H, can be modeled. Second, we recently added the electronegative element O, along with the associated charge terms, to the adaptive intermolecular REBO (AIREBO) potential (Stuart et al 2000 J. Chem. Phys. 112 6472). The resulting qAIREBO potential (Knippenberg et al 2012 J. Chem. Phys. 136 164701) makes use of the bond-order potential/split-charge (BOP/SQE) equilibration method (Mikulski et al 2009 J. Chem. Phys. 131 241105) and the Lagrangian approach to charge dynamics (Rick et al 1994 J. Chem. Phys. 101 6141). The integration of these two techniques allows for atomic charges to evolve with time during MD simulations: as a result, chemical reactions can be modeled in C-, O-, and H-containing systems. The usefulness of the 2B-SiCH potential for tribological investigations is demonstrated in molecular dynamics (MD) simulations of axisymmetric tips composed of Si and SiC placed in sliding contact with diamond(1 1 1) surfaces with varying amounts of hydrogen termination. The qAIREBO potential is used to investigate confinement of sub-monolayer coverages of water between nanostructured surfaces.