It was recalled that the boundary conditions usually affected the results of computer simulations of defects; especially in the case of extended defects such as a straight dislocation, where a model-size dependence of the result was sometimes observed. A flexible boundary condition was developed here, for the simulation of a moving dislocation, by using the Lagrange principle. Using the flexible boundary condition, various properties of a screw dislocation (stable core structure, Peierls stress, etc.) were calculated within a square lattice. Contrary to the present flexible boundary condition, an explicit size-dependence was observed in the case of a rigid boundary condition; due to a strong image force which arose from the boundary. However, it was observed that the result tended to approach that for the flexible-boundary model as the size of the model lattice was increased. In the case of a screw dislocation with a Peierls stress that was greater than 0.01G, the flexible boundary condition was not available because high-frequency lattice vibrations were emitted from the dislocation line during glide and the boundary could not respond to these waves.

Flexible Boundary Condition for a Moving Dislocation. K.Ohsawa, E.Kuramoto: Journal of Applied Physics, 1999, 86[1], 179-85