Adsorption of Adenine and Thymine and Their Radicals on Single-Wall Carbon Nanotubes

Abstract

The adsorption of adenine, thymine, and their radicals on the surfaces of metallic and semiconducting single-wall carbon nanotubes are studied by local density approximation within density functional theory. The energies and equilibrium distances for several configurations are obtained after relaxation of the entire system. The changes of the molecular bonds and angles before and after adsorption are also calculated. We find that all molecules are physisorbed due to the interaction of their π-orbitals and the π-orbitals of the nanotubes. The electronic structure of both metallic and semiconducting nanotubes is not changed significantly upon adsorption, and thus only small changes in the carbon nanotube properties are expected. The results from these studies can be used as a model of DNA interaction with the surfaces of carbon nanotubes.