FIG. 1.

(color online). Structure and energetics of the nano-oscillator. (a) Front view of the nano-oscillator. The nanotube is colored according to initial atomic partial charges q₀. Blue (H): positive; red (C1): negative. (b) Interaction energies between the potassium ion and the nanotube along the z-axis. The intervals used for the numerical fitting of the total potential to V (z) = c₀+c₂ z² are indicated by dashed lines (see text). (c) Force acting on the ion positioned along the z-axis. Comparison is made between a nonpolarizable nanotube model (dashed line), a polarizable nanotube model (solid line), and DFT calculations (solid circles). (d) Same as (b), but along the x-axis.