Structural, Electronic, and Mechanical Properties of Single-Walled Chrysotile Nanotube Models

Structural, electronic, and mechanical properties of single-walled chrysotile nanotubes have been investigated using the self-consistent charge density-functional tight-binding method (SCC-DFTB). The naturally occurring chrysotile nanotubes (NTs) are composed of brucite, Mg(OH)(2), layer in the outer side and tridynnite, SiO2, in the inner side. The zigzag (17,0)-(45,0) and armchair (9,9)-(29,29) chrysotile nanotubes, which correspond to the radii ranging from 16 to 47 angstrom. have been calculated. The SCC-DFTB results are in good agreement with available experimental and previously published theoretical results. The chrysotile nanotubes are estimated to be insulator with band gap of 10 eV independently of their chirality and size, and the Young's moduli are estimated to be in the range of 261-323 GPa. In addition, we have shown that the chirality of the NTs does not affect their stability, and the variant with brucite in the inner side and the tridymite in the outer side of the nanotube is indeed less stable with respect to the inverse case.