In this paper, a lattice-based cell model is proposed for single wall carbon nanotubes (SWNTs). The finite temperature effect is accounted for via the local harmonic approach. The equilibrium SWNT configurations are obtained by minimizing the Helmholtz free energy with respect to seven primary coordinate variables that are subjected to a chirality constraint. The calculated specific heats agree well with the experimental data, and at low temperature depend on the tube radii with small tubes having much lower values. Our calculated coefficients of thermal expansion (CTEs) are universally positive for all the radial, axial and circumferential directions, and increase with increasing temperature. The armchair tubes see very large circumferential CTEs, while the zigzag tubes see very large axial CTEs. The tube chirality affects mostly the axial and the circumferential CTEs, but not the radial CTEs.
|Number of pages||10|
|Journal||CMES - Computer Modeling in Engineering and Sciences|
|State||Published - 2006|