Mechanical and electronic properties of carbon and boron-nitride nanotubes

In this contribution we provide an overview of our recent work on the mecha nical and electronic properties of carbon and boron-nitride (BN) nanotubes, which are of key relevance to practical applications and to our present un derstanding of low-dimensional structures. On the mechanical properties we look at the nanotube axial stiffness, bending and torsion dynamics. We foun d that chiral tubes exhibit an interesting asymmetric torsional behaviour w ith respect to left and right twist that is absent in armchair or zig-zag t ubes. Topological defects are seen to modify slightly the mechanical respon se of the carbon network under applied strain. On the electronic properties we present an analysis of the role of the environment in nanotube density of states relevant for scanning tunneling spectroscopy (STS). Finally we pr esent results on the electronic density of states for BN nanotubes that can be used as a complementary fingerprint of those structures in STS experime nts and for their applications in composite (C-BN) electronic devices. (C) 2000 Elsevier Science Ltd. All rights reserved.