Using an empirical bond-order potential, molecular dynamics (MD) simulations, and lattice dynamics calculations, we study the thermal expansion of diamond, graphite and single-walled carbon nanotubes. MD simulations demonstrate that, while the C-C bond length increases at a similar rate with increasing temperature in all structures, the thermal expansion coefficient varies greatly in a manner consistent with experiment. An analysis of the mode-dependent Grüneisen parameters provides a detailed picture of how structure influences the competition between various vibrational modes associated with negative and positive Grüneisen parameters in determining the overall thermal expansion coefficient.

• Received 10 March 2003

DOI:https://doi.org/10.1103/PhysRevB.68.035425