Potential energy distributions within and on single-walled and double-walled carbon nanotubes

The potential fields arising from dispersion forces induced by single- and double-walled carbon nanotubes of various chiral configurations and sizes on an argon test atom have been calculated, employing a discrete summation method that takes into account the translational symmetry of the carbon lattice of the different armchair and zigzag chiral conformations. The total interaction potential was considered to be pair-wise additive and described by the Lennard-Jones 6-12 potential expression. This has yielded radial field distributions as a function of axial distance within, outside, and between the walls these carbon nanotubes. It was found that these distributions depended not only upon position but also upon orientation of the axes with respect to the graphene sheets. The potential barriers at the open end of the carbon nanotubes have also been studied. The effect of surface curvature was evaluated by comparing a single graphite sheet to the corresponding segments of nanotubes containing the same number of carbon atoms. Using the calculated data, the Henry constants and diffusion coefficients have been computed together with their temperature dependencies and compared to other planar and microporous carbon systems