Phase transition and elastic constants of CaO from first-principle calculations

The structural B1-B2 phase transition of CaO and the elastic properties of the B1 phase of CaO are investigated by ab initio plane-wave pseudopotential density functional theory method. The dependences of the elastic constants c(ij), the aggregate elastic modulus B-s and G, the elastic anisotropic parameter A, and the Debye temperature Theta(D) on pressure are successfully discussed. From the usual condition of equal enthalpies, we find that the structural B1-B2 phase transition of CaO occurs at 62.8GPa, consistent with the experimental value 61 GPa. From our elastic constants of CaO under pressure, we find that the B1-B2 structural transformation occurs at about 178 GPa by the elastic instability, which is far higher than the transition pressure 62.8 GPa. (c) 2006 Elsevier B.V. All rights reserved.