Elastic properties of quaternary oxypnictides LaOFeAs and LaOFeP as basic phases for new 26–52 K superconducting materials from first principles

The full-potential linearized augmented plane wave method with a generalized gradient approximation for the exchange-correlation potential has been applied to predict the elastic properties of quaternary oxypnictides LaOFePn (Pn = As and P) as the basic phases for the newly discovered 26–52 K superconductors. The optimized lattice parameters, independent elastic constants (Cij), bulk moduli, compressibility and shear moduli are evaluated and discussed. Numerical estimates of the elastic parameters of the polycrystalline LaOFePn ceramics are performed for the first time.