Density functional theory study of potassium atom adsorbing on the interior and exterior of a series of carbon nanotubes

Density functional theory was applied to study the adsorption of potassium atoms on the interior and exterior of a series of carbon nanotubes. It is found that K atoms can stably adsorb on the interior and exterior of a carbon nanotube. A K atom adsorbs at the center or near the sidewall on the interior of a carbon nanotube, but a K atom will only adsorb near the sidewall on the exterior of a carbon nanotube. The interior of a small-radius carbon nanotube is not favorable for K-atom adsorption, due to repulsive interaction. The interior of a medium-radius carbon nanotube is more favorable for K atom adsorption because of the interaction of the K atom with multiple carbon rings. We also investigate the K atom in regard to adsorption distance, Mulliken population, and the redistribution of electron density.