Mechanical and electronic properties of graphitic carbon nitride sheet: First-principles calculations

In this work, mechanical properties, elastic constants and the strain responses on the electronic properties of graphitic heptazine are investigated using density functional theory. The computed lattice constant and bulk modulus are in good agreement with the available literatures. The in-plane stiffness compared well with a similar two-dimensional structure, whereas the Poisson's ratio value is close to that of graphene. The calculated critical points (elastic and yielding points) for both the uni- and bi-axial strains indicate that the heptazine material can withstand longer tensions in the plastic region. This shows that the heptazine sheet is mechanically stable. Our calculations also predict enhanced band gap induced by small amount of bi-axial tensile strain within the elastic region. The increase in band gap is a result of symmetric deformations which predominantly affect the structural features of the sheet, leading to the eventual reorientation in the atomic orbitals of the sheet. We find no change in the electronic properties of the sheet under electric field up to a peak value of 10 V/nm. Such properties may serve as a guide for future nanodevice applications.