Stability and electronic structures of double-walled armchair germanium carbide nanotubes

Abstract

First-principle calculations based on density functional theory have been used to investigate the stability and electronic structures of double-walled (n1, n1)-(n2, n2) (4 ≤ n1 ≤ 8, n1 + 3 ≤ n2 ≤ n1 + 6) germanium carbide nanotubes (GeCNTs). For any given (n1, n1) inner tube, the corresponding (n1, n1)-(n1 + 5, n1 + 5) GeCNT has the highest formation energy and binding energy per atom, which indicate that the (n1, n1)-(n1 + 5, n1 + 5) nanotube is stable. The (5, 5)-(10, 10) GeCNT has been found to be a particularly stable geometry. The interlayer interaction between the two layers of the double-walled GeCNT leads to an obvious coupling, which results in a narrowing of the band gap