Furthermore, from Figure , the reduction in slope indicates that the maximum relative displacement of grains before the sliding event occurred became a weaker function of the number of layers when aluminum is added to the system. A notable observation for systems with aluminum is, that even though there is an increasing amount of rigid Si-Si bonds as the number of layers per GB increases, this has no significant impact on the sliding indicating that the aluminum at the GB plays a major role in facilitating sliding. In the presence of Al at the GB, a displacement between grains results in an equivalent shear at the GB interface because this is the weakest part. In the case of pure silicon, the deformation is distributed within the grain and at the GB interface. Understanding Bonding in the GB using COHP