The interaction and diffusion of lithium atoms in a (5,5) carbon nanotube were studied using density-functional theory. The Li-nanotube interaction perpendicular to the tube axis, for a single Li inside and outside the tube, was calculated and compared with the Li-graphene interaction deduced using the same technique. Both interactions were similar in the repulsive region but exhibited differences in their attractive part. They could nevertheless be described using a common parametrization. The Li-Li interaction was calculated as a function of their separation within the tube. This interaction was similar to a screened repulsive Coulomb potential at small separations. At greater separations, the Li-Li interaction did not vanish and exhibited residual oscillations. This repulsive long-range interaction favored the concerted diffusion of many Li atoms, as compared with the independent diffusion of individual Li atoms inside the tube.

Interaction and Concerted Diffusion of Lithium in a (5,5) Carbon Nanotube. M.Khantha, N.A.Cordero, J.A.Alonso, M.Cawkwell, L.A.Girifalco: Physical Review B, 2008, 78[11], 115430