Intrinsic grain boundary shear coupling tensor

Grain boundary (GB) migration stands as a linchpin process governing microstructural evolution in polycrystalline materials. Over the past decade, the concept of shear coupling, quantified through the shear coupling factor, has transformed our understanding and driven the development of theoretical frameworks for unifying GB behaviors. In this study, we introduced a novel concept of shear coupling strength designed to overcome the limitations of the conventional shear coupling factor, notably its deficiency in conveying "coupling" information. The shear coupling tensor formed by the shear coupling strengths characterizes intrinsic shear coupling properties across diverse GBs and reveals complex dynamics within the GB mobility tensor. The molecular dynamics simulation confirms the symmetry of the GB mobility tensor. This symmetry is inherently built into the shear coupling strength, aligning with an assumption made in previous studies. Additionally, an efficient methodology has been developed for streamlined extraction of both shear coupling and GB mobility tensors from atomistic simulations. This advancement holds the potential to sample GB behavior across extensive datasets, significantly enhancing our ability to predict structure-property relationships within the expansive 5-parameter space of GBs.