TY - EJOU AU - Yang, Liu AU - Han, Jie AU - Anantram, M. P. AU - Jaffe, Richard L. TI - Bonding Geometry and Bandgap Changes of Carbon Nanotubes Under Uniaxial and Torsional Strain T2 - Computer Modeling in Engineering \& Sciences PY - 2002 VL - 3 IS - 5 SN - 1526-1506 AB - Bonding geometry and bandgap of carbon nantotubes under uniaxial and torsional deformation are studied computationally for nanotubes of various chiralities and diameters. Bonding geometries are obtained with Tersoff-Brenner potential from molecular mechanics simulations. Bandgaps as function of strain are calculated from the molecular mechanics structures using one (p) and four (2s and 2px, 2py, 2pz) orbital tight-binding models. For small strains, the bandgap results are qualitatively consistent with those predicted by the one orbital analytical model. Response of the electronic properties of nanotubes to large strains is characterized by a change in sign of d(bandgap)/d(strain). These originate from either quantum number or bonding geometry effects, and are strain-induced semiconductor-metal transitions. The effect of variations in bonding geometries between continuum mechanics and molecular mechanics structures on the electronic properties and differences between the one and four orbital models are also presented. KW - DO - 10.3970/cmes.2002.003.675