▎ 摘　　要

The shielding tensor in C-13 nuclear magnetic resonance (NMR) offers important information about the structural aspects of carbon materials from a local point of view. Not only the symmetry of the carbon site but also the presence of local structural distortions can affect the values of the isotropic shielding constant, the shielding anisotropy, and the deviation from axial symmetry. In this report, the C-13 shielding in a single graphene sheet was calculated using density functional theory (DFT) via the gauge-including projector augmented plane wave (GIPAW) method. After performing convergence tests involving changes of k sampling and supercell size, the calculations were extended to graphene-based systems, including graphene bilayer and stacked graphene sheets, finally leading to hexagonal graphite. The calculated results showed good agreement with experimental values obtained by C-13 NMR measurements in different types of carbon materials, evidencing the power of the DFT calculations for predicting NMR parameters in graphene-based nanocarbons.