First-principles calculations of structural, electronic and elastic properties of carbon allotropes

Recently, carbon allotropes have attracted people's attention again. Here, we aim to mainly study the structural, electronic properties and Raman spectra of 2H-D, 4H-D, 6H-D, 8H-D, 10H-ID and 10H-IID under pressure (0–70 GPa) by using first-principles calculations with density functional theory. The results show that the pressure in this range has less effect on the structural and electronic properties, but it has a relatively large effect on Raman spectrum. However, 6H-D and 8H-D under high pressure are not easy to determine which one is by Raman spectrum. In addition, the elastic and thermal properties at zero pressure were studied. Their independent elastic constants, bulk modulus, shear modulus, Pugh's ratio, Young's modulus, Vickers hardness, Debye temperature, average sound velocity and minimum thermal conductivity were given. They are comparable to those of diamond and agree with previous studies. Last but not the least, the Debye temperature and thermal conductivity increase with the increasing hexagonal content.