Evaluation and Extension of ReaxFF Reactive Force Field Method for Applications to Dielectric Oxides and their Multi-Material Interfaces

The ReaxFF reactive force field method was extended to BaTiO3. This extension combines earlier published ReaxFF descriptions for Ba and Ti oxides with additional training for a BaTiOH force field against Density Functional Theory DFT data describing volumeenergy relations, defect formation and migrations, and deformations of BaTiO3crystal structures. We reproduce the DFT data without requiring change to the ReaxFF formulism, which means that these parameters are fully transferable with all earlier ReaxFF sets, including those for organic molecules and different inorganic systems. This parameter set was used in molecular dynamics MD simulations. We observe clear ferroelectric FE to nonferroelectrictransition for bulk BaTiO3, and show how different surface terminations can affect the FE response. ReaxFF provides a unique, computational efficient, tool for studying FE response in realistic, complex materials.