Size dependence of thermal properties of armchair carbon nanotubes: a first-principles study

Abstract

The authors use first-principles pseudopotential-based density functional theory calculations of phonon dispersions to determine the size dependence of thermal properties of armchair single wall carbon nanotubes (SWCNTs), such as their negative thermal expansion and specific heat. While the specific heat is found to depend rather weakly on the diameter of SWCNTs, their negative thermal expansion behavior determined within a quasiharmonic approximation (QHA) exhibits a relatively strong dependence on the diameter. They identify the low energy vibrational modes that are responsible for the negative thermal expansion.