Computer Simulation of Grain Boundary Structures in Minerals

Computer Simulation of Grain Boundary Structures in Minerals B.B. Karki1 and R. Kumar1 Summary We report important preliminary results from atomistic simulations of grain boundaries in minerals. The recently developed parallel PCMD (polycrystal molecular dynamics) program was used to perform structural optimization. In particular, we have simulated the {310}/[001] symmetric tilt grain boundary of MgO as a function of pressure. The simulation cell containing about 55,000 atoms was used. Visualization of the atomic position-time series data show that the structure changes dramatically on compression from a simple open-structure at zero pressure to a highly dense structure containing high coordination state and a screw-like dislocation at high pressure, consistent with previous atomistic simulations. Our future directions include the study of more grain boundaries in this and other minerals. With knowledge about various candidate structures for a given boundary, we will optimize them further using the first-principles molecular dynamics method based on density functional theory.