First-principles Calculations Of Electronic Structure And Mechanical Property Of TiN

Recently, the first-principles calculations based on density functional theory(DFT) make remarkable progress. It is current method in scientific field and is applied to condense mater, materials science, computer science, geophysics, chemistry and biology, and so on.Titanium nitride, which is in the rocksalt structure and is known as a ceramic material, exhibits a series of physical properties of high hardness, high intensity and high melting point and so on. It is widely used in many industries. Many first-principles studies on the bulk properties of 3d transition metals in which TiN is included have been done abroad and some calculations of the properties of TiN have been done in our country.In this paper, the electronic structure and mechanical property were studied by using Vienna Ab-initio Simulation Package(VASP) in the scheme of the density functional theory(DFT) and generalized gradient approximation(GGA) on which the first-principles calculations method is based. The equilibrium lattice constant has been optimized as 4.26 A, which was above the experimental value for 0.02 A, and the error was only 0.5%, so it was in good agreement with published value. After the picture of energy-band structure and density of state(DOS) were plotted, we can affirmed that TiN belongs to metal and that the metallic property is primarily determined by 3d electron of Ti element. The cohesive energy and elastic constants which include shear modulus, bulk modulus and elastic modulus were calculated and the values of them were 14.08 eV, 211.84 GPa, 2.79 Mbar and 507.16 GPa, respectively. These results were compared with both available experimental data and results calculated by using other algorithms such as FLAPW-GGA, FLAPW, LMTO-ASA. The limit of density functional theory (DFT) arises the result that the value of bulk modulus was a little smaller and the shear modulus was a little bigger than the experimental data. The phenomena that the bulk modulus of TiN is much smaller than that of diamond is contrary to the fact that TiN has high hardness, so we desired to make more thorough study on the microstructure of TiN.