Oscillation of a CNT housed inside a naturally formed CNS. (a) Snapshots of the axial oscillation of the CNS-based nano-oscillator at 5, 15, 20, 30, 40, and 50 ps, respectively. Note the coupled axial oscillations of the CNT and the CNS itself. The evolution of (b) the absolute amplitude and (d) the relative amplitude of the CNT oscillation inside the CNS, as a function of simulation time, respectively. The FFT analysis of the absolute amplitude (c) and the relative amplitude (e) for the first 500 ps reveals a frequency of the oscillation of the CNT inside the CNS (29.4 GHz) and that of the oscillation of the CNS itself (50.9 GHz), respectively. The simulations are carried out at 100 K.