Atomistic studies of surface adhesions using molecular-dynamics simulations.

The existing theoretical descriptions of continuum surface adhesions, such as the JKR (Johnson-Kendall-Roberts) model, have been very useful for the interpretation of particle contacts of sizes down to micrometre length-scales. However, the continuum model is expected to fail at atomic length-scales, where discrete atomistic interactions become significant. The crossover length-scales at which the macroscopic phenomena begin to manifest themselves, and how they occur, are equally baffling and remain poorly understood. This paper explores the issue of atomistic surface contacts between two ionic bodies made of similar materials, such as MgO and NaCl, using molecular dynamics. A range of surface phenomenological behaviour has been identified, from simple fracture to plastic dislocation and neck formation, which are not predicted in continuum models. In addition, the influences of body structure with respect to surface contacts will also be discussed briefly.