HARMONIC-ANALYSIS OF LENNARD-JONES FCC GRAIN-BOUNDARIES

We present a harmonic analysis of symmetric tilt boundaries in face-ce ntred cubic Lennard-Jones systems with a view to finding their thermod ynamic properties. These results are used to predict those which are l ikely candidates for interface melting at high temperature. A system i s found in which the excess energy is monotonic with misorientation, b ut in which the excess entropies and stresses are not. The analysis sh ows that the presence of a grain boundary perturbs the high- and low-f requency modes by making them more localized at the boundary. Very loc alized split-off states outside the bulk continuum are also observed. Information on participation ratios, local densities of states and loc al coordination numbers helps to explain why such states exist.