First-principles Study on Effects of Pressure on Properties of B2 Intermetallic Compound YCu

The first-principles method based on density functional theory was used to study the lattice parameters, elastic properties, phonon spectra and electronic structures of B2 type intermetallic YCu at different pressures from 0 to 50 GPa. The results indicate the effect of pressure on the elastic constants is obvious, and the mechanical stability of the crystal structure is good in the range of 0-40 GPa. With the increase of pressure, the bulk modulus B increases linearly; the shear modulus G and Young’s modulus E increase first, and decrease significantly at 30 GPa, and then continued to increase. From 0 to 20 GPa,YCu can exist stably on the kinetics; from 30 to 50 GPa, the system does not satisfy the kinetic stability, and phase transition occurs. The state density of all structures at the Fermi level is not 0, indicating that the system exhibits a certain degree of metallicity. From the PDOS, the electronic states near the Fermi level are mainly contributed by p and d orbital of the Y atom,while Cu atom does not contribute substantially to the electronic states near Fermi level.