Force-based interatomic potential for strength and toughness in brittle solids

Most of the available potentials (such as Tersoff, Stillinger-Weber, ReaxFF, EDIP, Vashishta, etc.) produce reliable properties (such as bulk modulus) of a solid under symmetry-preserving deformation or symmetry-breaking deformation around the linear regime of mechanical deformation. However, despite the incorporation of long-range interactions, they have sizable accuracies in producing extreme mechanical properties such as strength and toughness (which are two critical extreme mechanical properties of a solid). To address the limitations, we developed a force-based scheme that gives first-principles accurate strength and toughness. We validated the approach for a number of brittle solids including diamond, SiC, hBN, and graphene. In addition to fitting the equilibrium material properties, the approach allows fitting the potential to the forcing behavior as well as the mechanical strength of the solid, without requiring any ad hoc modifications of the nearest-neighbor interactions to avoid artificial stiffening at larger deformation. The talk will discuss the development of the force-based scheme and its application for a number of brittle solids. It will highlight a number of failure mechanisms that emerge from an accurate description of the interatomic interactions.