The free energy of grain boundaries from atomistic computer simulation

Abstract: A novel thermodynamic integration (TI) scheme is presented that allows computing the free energy of grain boundaries (GBs) in crystals from atomistic computer simulation. Unlike previous approaches, the method can be applied at arbitrary temperatures and allows for a systematic extrapolation to the thermodynamic limit. It is applied to a $\Sigma11$ GB in a face centered cubic (FCC) Lennard-Jones crystal. At a constant density, the GB free energy shows a non-monotonic temperature dependence with a maximum at about half the melting temperature and the GB changes from a rigid to a rough interface with distinct finite size scaling above this temperature.