Analytical potential functions based on force-fields for studying the Dynamics of vibrationally excited and reactive carbon nanotubes interacting with aminoacids

Analytical potential functions based on force-fields usually employed in Molecular Dynamics simulations are constructed for studying vibrationally excited and reactive carbon nanotubes interacting with aminoacids. The proposed method is illustrated by producing an all-atom potential energy surface of a (5, 5)-capped carbon nanotube with a N-centered glycine radical. It is demonstrated that by parametrizing separately the short and long range carbon-nitrogen interactions and interpolating them by proper switching functions we can construct an analytical potential which fits calculated density functional theory points along the reaction path described by the (C_tube-N _glycine) bond. Vibrational spectra obtained from classical mechanical trajectories reveal regular localized motions for excitation energies below the barrier of dissociation. Regularity of the motions is further confirmed by locating families of stable periodic orbits. These results validate the use of (semi)classical mechanics and encourage the investigation of larger nanotubes.