Carbon and silicon substitution in (4, 4) aluminum nitride nanotube — Density functional study of27Al and14N electric field gradient tensors

Abstract

A computational study at the level of density functional theory (DFT) was performed to investigate the influence of Si and C substitution on the14N and27Al quadrupole coupling constants (CQ) in the armchair single-walled aluminum nitride nanotube (SWAlNNT). To this aim, a 1 nm AlNNT consisting of 28 Al and 28 N atoms was considered in which both mouths of the nanotube are capped by hydrogen atoms. Additionally, two other forms of this model of AlNNT were considered in which five Si and five C atoms were substituted in place of the five Al and five N atoms, with two rings in the length of nanotube, like a wire, in the first form; and three Si and three C atoms were substituted in place of three Al and three N atoms as a central ring on the surface of the AlNNT in the second form. The calculated CQvalues for three optimized AlNNT systems (raw and Si- and C-substituted) reveal diverse electronic environments in the above-mentioned systems. All the calculations were carried out using the Gaussian 98 software package.Key words: armchair nanotube, density functional theory, nuclear quadrupole resonance.