A local instability criterion for solid-state defects

The loss of mechanical stability is a general phenomenon that underlies a wide variety of features in the behavior of crystalline materials. In this paper, we present an instability criterion that is of general applicability, subject to the restriction of low temperatures. The criterion is applied to two situations, that of hydrostatically induced cavitation and of quasi-brittle crack growth due to mode I loading. As judged by the results of independent molecular statics simulations, the predictions of the criterion are quite accurate.