First-principle study on the physical properties of ultra-incompressible ReB2

The elastic and physical characteristics of ReB2 crystal have been predicted through a method of density functional theory within the generalized gradient approximation (GGA). Five independent elastic constants are C11=662 GPa, C12=150 GPa, C13=146 GPa, C33=1090 GPa and C44=263 GPa. The bulk modulus (B), shear modulus (G), Young s modulus (E), Poisson s ratio (γ) and the ratio of linear compressibility coefficient along the a- and c-axis crystal direction (Ka/Kc) are 356 GPa, 305 GPa, 711 GPa, 0.167 and 1.758, respectively. In addition, the dependence of bulk modulus (B) on temperature (T) and pressure (p) as well as the coefficient of thermal expansion (αL) at various temperatures are evaluated and discussed. The coefficient of thermal expansion is consistent with the famous Grüneisen s law when the temperature is less than 1500 K. Our results agree well with the other experimental results.