Molecular dynamics is a method to directly simulate motion of atoms. We are using this method to analyze deformation and fracture behavior of rock. So far, some 2-D and 3-D analyses were carried out on very small NaCl crystal. And it has been clarified that the simulation show bigger strength in compression than that in tension, inelastic deformation, strain softening and increase in strength with lateral pressure.
These characteristics resemble actual brittle rock. Note that the model dimension at peak load along the loading axis decreases with lateral pressure but the model dimensions in lateral directions do not depend on the lateral pressure. Namely, tensile strain criterion also stands in this simulation.
There are grain boundaries, microcracks, pores and impurities in actual rock. However, this approach seems to be an important one to start, from the micromechanical view, to built a new theoretical basis for rock fracture.