摘要: Uniform motion of a screw dislocation is studied in simple cubic lattice which atoms interact piecewise harmonically with nearest neighbours. The stress σ required for keeping the velocity v given exactly. excites waves k by ω( )= · , where ) dispersion relation and not restricted within first Brillouin zone. In contrast to continuum approximation, there no singularity at = c ; sound velocity. At low velocities (\(v{\lesssim}c/3\)), σ( has many singular points reflecting van Hove singularities.