Molecular dynamics study of high-temperature grain-boundary stability in a (100) sigma = 29 bicrystal model

A new molecular dynamics program for the investigation of planar bicrystalline interfaces at high temperature and finite external stress has been developed. The constant-stress (Parrinello-Rahman) method is combined with a Region 1-Region 2 treatment of the borders, thus avoiding (1) 3d-periodic border conditions (and therefore the presence of two interfaces in the computational unit cell) and (2) unphysical constraints arising from fixed borders. The usefulness of this new semi-periodic border treatment is illustrated in an investigation of the high-temperature stability and structure of the sigma = 29 (100) twist grain boundary.