DFT study on elastic and piezoelectric properties of tetragonal BaTiO3

A theoretical method for studying the mechanism of the piezoelectric effects in crystals from first-principles calculations is described and applied for tetragonal BaTiO3 in the present work. The elastic constants of tetragonal BaTiO3 are calculated by using the homogeneous deformation method in the scheme of density-functional theory and the generalized gradient approximation. The bulk modulus and the Debye temperature are also calculated from the elastic constants and found to be in good agreement with corresponding experimental values.