First-principles calculation of the electronic properties and external force modulation of a new tetragonal structure C3N2 crystal

A new tetragonal structure of C3N2 was discovered through the method of atom replacement, which is a superhard structure with a hardness of 54 GPa. The structure, elasticity and electronic properties of C3N2 under hydrostatic pressure and biaxial strain are studied in detail by the first principle calculation. The results show that the structure keeps mechanical and dynamic stability. Among them, Young's modulus and shear modulus are relatively large, reaching 821 GPa and 358 GPa, respectively. All elastic constants and elastic moduli increase (decrease) with increasing pressure and compressive (tensile) strain. The HSE06 hybrid function calculation shows that C3N2 is an indirect bandgap semiconductor with a bandgap of 1.403 eV can be regulated by pressure and biaxial strain. In the process of applying biaxial strain, the position of the bottom of the conduction band changes from point A to point G. At the same time, it provides new structures and ideas for potential superhard carbon and nitrogen compounds.