Energy dispersion in graphene and carbon nanotubes and molecular encapsulation in nanotubes

Density-functional calculations of electronic and vibrational dispersion energies for pristine graphite monolayer (graphene) and single-walled carbon nanotubes (SWCNTs) are presented. Optimized parameters for nonlocal norm-preserving pseudopotentials which replace the potential field due to core electrons are given. Comparison with observations, where available, is made. The effect of encapsulation of carbon nanotubes with an alkali-halide matrix is numerically investigated. The electronic band structure of encapsulated SWCNT is noticeably modified, as is its charge density, and hence its optical properties.