Nanotube devices: A microscopic model

A microscopic model is developed for calculating electrostatic properties of nanotube devices. It is shown that the quantum-mechanical approach yields the same results as the statistical calculation in the limit of a thin tube suspended over a conducting gate at a distance exceeding the nanotube radius. A closed analytic expression is obtained for the atomistic capacitance of a straight nanotube and for a nanotube with a modest curvature. This method allows the fast and exact calculation of device parameters for the nanotube electromechanical systems and nanotube electronic devices.