Molecular dynamics study of temperature-induced structural changes in YBa2Cu3O7 crystal

The structure of YBa2Cu3O7 crystal has been studied with the aid of molecular-dynamics (MD) technique. A two-body model potentials proposed by Zhang and Catlow have been used in MD simulations performed in wide range of temperature. The temperature-induced orthorhombic-to-tetragonal phase transition is observed. The distruction of the arrangement of atoms in the CuO chains due to diffusion of oxygen atoms is observed. The diffusion coefficients are calculated, and their variation as a function of temperature is analysed. The activation energy is estimated.