Development of a ReaxFF description of gold oxides and initial application to cold welding of partially oxidized gold surfaces

We present the ReaxFF reactive force field methodology for modeling a gold-oxygen binary system. The force field parameters were fitted against a data set including equations of state, heats of formation and binding energies derived from DFT calculations. The trained force field was then used to study the diffusion properties of oxygen on a gold surface. The diffusion study shows that oxygen atoms have a relatively low mobility on the gold surface. We also present a prospective application of this force field by performing molecular dynamics simulations studying the effect of oxidation level on contact strength of a cold welded joint. The results indicate that low levels of oxidation can significantly impact the joint cohesive energy.