On reliability of molecular statics simulations of plasticity in crystals

A perfect 3D BCC crystal is subjected to tensile deformation, using a molecular statics approach, in order to investigate the reliability of the plastic part of the stress–strain data. The uniqueness of the stress–strain data serves as a criterion for the assessment of simulation reliability. Three magnitudes of displacement increments are considered for this purpose. For each magnitude the convergence criterion of relaxation to a minimum energy state is set the same. It is shown that the magnitude of the displacement increment does affect the stress–strain data and, for a given convergence criterion, there is a minimum magnitude below which the plastic part of the stress–strain data does not change. The related issue of dislocation formation at different displacement increments is also addressed.