Modeling of a structural phase transition in La2-xSrxCuO4

The structural, vibrational, and elastic properties of La2CuO4 are calculat ed using a model for calculating the energy of the crystal based on interio nic potentials with the multiparticle Jahn-Teller contribution included exp licitly. The microscopic reasons for the structural instability of the La2C uO4 lattice relative to rotations of the oxygen octahedra are investigated. A structural phase transition from the orthorhombic phase (space group D-2 h(18)) into the tetragonal phase (space group D-4h(17)) under hydrostatic c ompression of an La2-xSrxCuO4 crystal is modeled. The (P,x) structural phas e diagram for La2-xSrxCuO4 is constructed. (C) 1999 American Institute of P hysics. [S1063-7834(99)03606-0].