First-principles calculations for elastic properties of rutile TiO₂ under pressure

This paper studies the equilibrium structure parameters and the dependences of the elastic properties on pressure for rutile TiO_2 by using the Cambridge Serial Total Energy Package (CASTEP) program in the frame of density functional theory. The obtained equilibrium structure parameters, bulk modulus B_0 and its pressure derivative B'_0 are in good agreement with experiments and the theoretical results. The six independent elastic constants of rutile TiO_2 under pressure are theoretically investigated for the first time. It is found that, as pressure increases, the elastic constants C_11, C_33, C_66, C_12 and C_13 increase, the variation of elastic constant C_44 is not obvious and the anisotropy will weaken.