Magnetic response and NMR spectra of carbon nanotubes fromab initiocalculations

Abstract

We present ab initio calculations of the magnetic susceptibility and of the 13 C chemical shift for carbon nanotubes, both isolated and in bundles. These calculations are performed using the recently proposed gauge-including projector augmented-wave approach for the calculation of magnetic response in periodic insulating systems. We have focused on the semiconducting zigzag nanotubes with diameters ranging from 0.6 to 1.6 nm. Both the susceptibility and the isotropic shift exhibit a dependence with the diameter (D) and the chirality of the tube (although this dependence is stronger for the susceptibility). The isotropic shift behaves asymptotically as α/D + 116.0, where α is a different constant for each family of nanotubes. For a tube diameter of around 1.2 nm, a value normally found in experimental samples, our results are in excellent agreement with experiments. Moreover, we calculated the chemical shift of a double-wall tube. We found a diamagnetic shift of the isotropic lines corresponding to the atoms of the inner tube due to the effect of the outer tube. This shift is in good agreement with recent experiments, and can be easily explained by demagnetizing currents circulating the outer tube.

Density Functional Theory Calculations of 95Mo NMR Parameters in Solid‐State Compounds

“…A number of applications to organic compounds have also been performed and were reviewed in 2007 by Harris et al [72] Periodic conditions have also been used to study more accurately a range of problems in carbon nanotube science, such as the influence of defects, nanotube diameter and functionalisation. [73][74][75][76][77][78] Recently, the first application to 3d transition metals has been performed for V and Ti. [79,80] To study large systems containing heavier transition metals, such as molybdenum, the PAW and GIPAW methods have to be tested as they have never been applied to the calculation of core properties of 4d elements.…”

First principles nuclear magnetic resonance signatures of graphene oxide

“…As a commonly used method, the calculated 13 C chemical shift of benzene was used to calibrate the chemical shift for other systems, [29,30] which generally leads to a quantitative agreement between theory and experiment. The isotropic chemical shift of benzene molecule calculated using a cubic cell of 15×15×10Å 3 was 42.2 ppm, agreeing well with previous studies.…”

“…[29][30][31][32][33][34] 13 C NMR isotropic chemical shifts of pristine CNTs, based on the density functional theory (DFT) and an infinite CNT model, depend on the electronic structure and the diameter but not on the chirality. [31] It has also been demonstrated that a wealth of knowledge on functionalizations [32,34] and defects [33] of CNTs can be obtained from NMR simulations.…”

Electric and Magnetic Response of Multi-Wall Carbon Nanotubes

“…There have been several reports on NMR in nonaligned nanotubes, both experimental [39][40][41][42][43][44][45][46][47] and theoretical. 16,[48][49][50] First, we should note that the field varies discontinuously on the cylinder surface due to the induced surface current. The field at a carbon nucleus is given by the average of that of the outside and inside of the cylinder surface.…”

“…5,6) This leads to a strong tendency of nanotubes to align in the direction of a magnetic field, which has been used for experimental observation [7][8][9][10][11] of the Aharonov-Bohm effect on the band gap predicted theoretically. [12][13][14] Response of a single-wall nanotube to a magnetic field was studied also in a tight-binding model 15) and ab-initio calculation, 16) and that to an electric field in a tight-binding model 17) and in a kÁp model. 18) In this paper, we shall calculate the distribution of induced electric and magnetic fields of single-wall carbon nanotubes and use the results for the study of dielectric screening effect and NMR lineshape in multi-wall nanotubes.…”