Role of the van der Waals forces in the ability of a double-walled carbon nanotube to accommodate a C60molecule: The example of C60@(15,0)@(24,0)

Abstract

We report the first nonempirical inclusion of the van der Waals interaction in the study of the ability of a double-walled carbon nanotube to accommodate a C${}_{60}$ molecule. In agreement with the experiments reported by Khlobystov et al. [A. N. Khlobystov, D. A. Britz, A. Ardavan, and G. A. D. Briggs, Phys. Rev. Lett. 92, 245507 (2004)] this ability is confirmed even when the diameter of the inner tube is small. The study considered for the prototype case of C${}_{60}@(15,0)@(24,0)$ suggests that when and only when the van der Waals interactions are included the encapsulation becomes exothermic, although it may require a finite energy barrier.