Permeation of Fullerenes through Graphynes: Theoretical Design of Nanomechanical Oscillators

Abstract

Carbon allotropes such as fullerenes, carbon nanotubes (CNTs), and graphene have shown great promise for device applications in recent times. Nanomechanical oscillators based on CNTs are well-explored theoretically as well as experimentally. Investigations on the motion of C60 through CNTs have revealed oscillator frequencies of up to 74 GHz. However, the absence of mature technology in the terahertz regime has resulted in the so-called terahertz gap. On the basis of an analysis of the permeation of fullerenes through the nanopores of graphynes (GYs), herein, we report the theoretical design of nanomechanical oscillators in the 0.1–0.5 THz regime. The design strategy involves employing electronic structure methods as well as atomistic model potentials to probe the permeation process of a set of fullerenes, namely, C20, C42, C50, C60, C70, and C84 through the triangular and the rhombus-like nanopores of γ-GY-N (N = 4–6) and r-GY-N (N = 4–5), respectively. Considering the results from the electronic structure methods as a benchmark, we adopt a fitting procedure to extract the optimal values of the parameters in the atomistic model potentials that could be useful for researchers performing force field calculations on fullerene–graphyne systems. Our findings indicate that a discrete atomistic potential of the improved Lennard-Jones type can describe the permeation process leading to the oscillatory response with reasonable accuracy at a computational cost much lower than the electronic structure calculations.