Localized plastic deformation in a model metallic glass: a survey of free volume and local force distributions

Plastic deformation of a model glass is investigated via large scale molecular dynamics simulations. The role of microscopic fluctuations of the structure for the deformation behavior is highlighted by demonstrating that statistically independent samples prepared via an identical protocol develop qualitatively distinct deformation paths. As a quantitative measure, the spatial distribution of the particle based excess volume is monitored via Voronoi tesselation. While the fluctuations of the thus defined single-particle based excess volume do not seem to show any signature of the strain field, a nonlocal definition of the excess volume clearly correlates with the observed shear deformation field. The distribution of the force acting on individual particles also shows a pattern strongly similar to that of the strain. In line with other studies, these results underline the importance of both the structural heterogeneities as well as the fluctuations of the locally acting forces and stresses for plastic deformation in amorphous solids.