Spectrum of Temperature-Dependent Rotational Frequency of the Rotor in a Thermally Diven Rotary Nanomotor

By fixing of the outer tube of double-walled carbon nanotubes, a thermally driven rotary nanomotor can be obtained one or more carbon atoms at the end of the stator have an obvious inward radial deviation. Due to the asymmetry of the potential field of the stator, a collision between two tubes leads to the axial component of angular momentum that drives the rotation of the rotor. Relative sliding between the two tubes is resisted due to the roughness of the potential field of stators. Hence, the rotational frequency of the rotor has a maximal value in the balanced state. The spectrum of rotational frequency with respect to temperatures from 8 to 2000 K is presented by means of molecular dynamics simulation. The temperature interval is divided into five zones on the basis of the characteristics of the spectrum. In the robust zone, the nanomotor exhibits stationary rotation. In the controllable zone, the rotational frequency of rotor can be adjusted by varying the temperature. In particular, if a rotating rotor is cooled to an ultralow temperature, the final stable value of the rotational frequency is still very high and is slightly lower than the maximal value rather than zero; i.e., the nanomotor will theoretically never stop rotating.