Charge Density Discrepancy Between NBO and QTAIM in Single-wall Armchair Carbon Nanotubes

Abstract

The relationship between the natural electron charge density in NBO (Natural Bond Orbital) and the electron charge density in QTAIM (Quantum Theory of Atoms in Molecules) of armchair single-walled carbon nanotubes (SWCNTs) with 13C chemical shift are studied at B3LYP/6-31G and B3LYP/6-311+G(d) computational levels. It is shown that increasing the positive electron charge density in NBO is accompanied with increase of the 13C chemical shift. In vice versa the increasing of positive electron charge density in QTAIM is accompanied with decrease of the 13C chemical shift. However there is no relationship between chemical shift and NBO charge with variation of 6-311+G(d) basis set instead 6-31G basis set.