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

Density functional theory has been applied to study of adsorption of lithium atom in the interior and exterior of a series of carbon nanotubes. It is found that lithium atom can steadily adsorb in the interior and exterior of carbon nanotube. Lithium atom adsorbs at the center and near the sidewall for interior of carbon nanotube, but lithium atom only adsorbs near the sidewall for exterior of carbon nanotube. The interior of small diameter carbon nanotube is more favorable than larger ones for lithium atom adsorbing. This is because the lithium atom almost locates at the center of small diameter carbon nanotube, leading to strong interaction. Moreover, we also investigate the lithium atom of adsorption distance, Mulliken population and the system of the redistribution of electron density.