Molecular-dynamics study of lattice-defect-nucleated melting in silicon

The high-temperature behavior of both a high-angle twist grain boundary and a free surface on the (110) plane of silicon are investigated using molecular dynamics and the Stillinger-Weber potential. It is found that, above the thermodynamic melting point, melting is nucleated at the grain boundary or surface and propagates through the system with a velocity that increases with temperature. We conclude that, due to the relatively fast nucleation times, melting in real crystals should be initiated at grain boundaries and surfaces, a conclusion that is entirely in accord with experiment.