First-Principles Investigation on the Tribological Properties of h-BN Bilayer Under Variable Load

Using first-principles method, for h-BN bilayer, we successfully probe the major factors of different low-friction paths in the three-dimensional potential energy surface (3D-PES) under variable loads. By means of the static PES and charge density difference analysis, we demonstrate how electrostatic interactions, with regard for van der Waals contributions at 0 nN, progressively impact the shape of 3D-PES and low-friction paths with increasing the normal load. Herein, the sliding properties of h-BN bilayers have a distinct relative orientation. Especially, the load-induced 3D-PES with variable shape is assigned to the band gap and repulsive van der Waals force. It is noted that the low friction not only is obtained for the commensurate layers under low loads, but also high ones.