Abstract
Molecular-dynamics simulations are performed to study graphene-based torsional mechanical resonators. The quality factor is calculated by QF=ωτ/2π, where the frequency ω and lifetime τ are obtained from the correlation function of the normal mode coordinate. Our simulations reveal the radius dependence of the quality factor as QF=2628/(22R− 1+0.004R2), which yields a maximum value at some proper radius R. This maximum point is due to the strong boundary effect in the torsional resonator, as disclosed by the temperature distribution in the resonator. Resulting from the same boundary effect, the quality factor shows a power law temperature dependence with power factors below 1.0. The theoretical results supply some valuable information for the manipulation of the quality factor in future experimental devices based on the torsional mechanical resonator.