Study of Cobalt Surface and Crystal Defect Behavior Using a Reactive Force Field (ReaxFF)

The reactive force field code ReaxFF differs from traditional force fields in that the bonds are not defined explicitly, but rather defined as a function of manybody interatomic distance, which allows for changes in bond order. This provides a valuable means by which large-scale reactive molecular dynamics can be performed without resorting to expensive quantum chemical ab initio methods. Periodic plane-wave density functional theory (DFT) calculations have been used to derive a ReaxFF parameter set for cobalt. These parameters have been used in a battery of calculations to evaluate the accuracy and performance with respect to other computational methods. We compare ReaxFF with additional DFT calculations, semi-emprical embedded-atom potentials, and experiments, for various large-scale bulk phase defect systems. We compare energetic, structural, and dynamic properties, were possible. In addition to defect systems, ReaxFF is used to examine simple surface behavior such as reconstruction and oxidation, ultimately providing insight into the role of cobalt in catalytic applications.