Negative differential friction predicted in a 2D GaInS3 homojunction with multiple sliding pathways

Derived by exploring the essence of friction from a microscopic perspective, the theory of negative differential friction involves an abnormal negative friction coefficient μ, which provides a way to research friction and has attracted much attention in recent years. Here, first-principles calculations are used to predict that negative μ as measured by the slope of corrugation in the sliding potential-energy barrier subject to an external load can be achieved when bilayer GaInS3 in commensurate contact slides relatively along the b-direction. Such remarkable observations can be attributed to the competition and alternating dominance of the van der Waals attraction regime and the electronic repulsion regime between the layers caused by variation of interlayer distance during pressurization. In addition, the transfer and redistribution of interlayer charges enhance the S–In and S–Ga ionic bonds of the maximum-energy configuration, further lowering the potential-energy corrugation and causing negative differential friction. This study not only identifies a material exhibiting a negative friction coefficient during relative sliding across multiple configurations but also uncovers the physical mechanism behind this phenomenon. These findings offer fresh theoretical insights and practical possibilities for addressing friction-related challenges.