Atomistic simulation of matter under stress: crossover from hard to soft materials

Atomistic simulation can give insights to the mechanical behavior of stressed crystalline hard materials. Theoretical strength, defined in the long wavelength limit through elastic stability criteria, or more generally in terms of soft vibrational modes in the deformed lattice, can be studied by direct simulation of stress–strain response. It is suggested that this approach may be applied as well to the understanding of structural instability (failure) in soft materials, with appropriate considerations of the microstructure characteristic of such systems. Simple observations are made on the effects on strength and deformation of structural features—disorder, voids, surfaces and interfaces—that are common to both classes of matter. An exploratory study of membrane rupture is discussed to illustrate the mechanistic details on void nucleation and growth that are available from atomistic simulations.