Proton diffusion in transition metal oxide: a reaxFF reactive molecular dynamics study

Simulations of proton diffusion process in transition metal oxide (TMO`s) and it`s functionalized material, was studied with ReaxFF, an atomically detailed reactive molecular dynamics method that naturally models the breaking and forming of bonds. In this work, the ReaxFF force-field was first expanded by training it with quantum mechanical data(DFT+U) of the formation energy, surface energy, equation of state, bulk modulus, heat of formation and thermal expansion at different temperature of the TMO`s and related functionalized material, along with the data from earlier studies that describes TM−TM, TM−O, and TM−H interactions. This expanded ReaxFF force field is capable of simultaneously describing both TM−O and TM−O−H bonding interactions. Using the force field, simulations were performed at various temperatures (in the range of 0.1K to 850 K), and the trajectories of the layered structure were analyzed and systematically examined the proton diffusion in between the layers.