Theoretical prediction and regulation of interlayer stable angle in twisting bilayer graphene

Recent researches showed that interlayer rotation, as a control method, can effectively regulate the mechanical, electrical, and optical properties of two-dimensional (2D) materials. The control of the twisting angle and its stability influence the properties of rotation-tunable electronics, so it has attracted much attention. In this research, based on the Lennard-Jones (L-J) potential and energy density method, the energy landscape of twisted bilayer graphene (tBLG) is studied. The dependence of the locally stable twisting angle and the number of potential energy barriers on the size of the top layer graphene is analyzed. It is found that the size effect is related to the vertical distance between carbon atoms and the rotation axis. The large-sized top layer graphene has a larger energy barrier and higher stability under the same conditions, which is conducive to the structural stability of the rotation-tunable electronics. The vacancy defect and the shape of the top layer graphene have an effect on the energy landscape, based on which the regulation of stable twisting angle can be achieved. In addition, the effect of the position of the top layer graphene on the energy landscape is studied, and it is found that the energy landscape has a 2D periodicity with the change of the position, which is related to the lattice structure of graphene. There are two main modes of energy landscape with the variation of the position of top layer graphene, and the changing trend is similar under the same mode. Our research predicts the interlayer stable twisting angle theoretically and provides theoretical support for the design of rotation-tunable electronics.