Silicon–carbon vs. carbon nanotubes at DFT: Aromaticity, polarizability, and structural network(s) at various lengths and widths

Optimization of finite-length armchair single-wall silicon carbon nanotubes (SiCNTs), with alternating carbon and silicon bonds, exhibit only one structural network, whereas the carbon nanotubes (CNTs) show three different classes of networks at different (succeeding) tubular lengths. The SiCNTs immerge in a clear contrast to the CNTs which demonstrate strong ring currents, bond length variations, and the abrupt changes of ΔELUMO–HOMO, as the tube elongates. In addition, the magnitudes of polarizability tensors increase as functions of length and width for the SiCNTs, which appear ∼2 folds higher than the CNTs with the same number of atoms.