Elastic properties of rare earth pyrochlores R2Ti2O7 (R = Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu): Ab initio calculations

Abstract The experimental elastic constants of R 2 Ti 2 O 7 (R = Gd–Lu), in particular for R = Tb, Dy, Ho published in scientific literature up to now are slightly different, so this makes an ab initio investigation of the current elastic constants for the whole rare-earth row R 2 Ti 2 O 7 (R = Gd-Lu). The aim of this paper is to give the ab initio calculations of the structural and elastic properties for a whole row of rare-earth titanate pyrochlores in terms of the MO LCAO approximation, using hybrid DFT Hamiltonian PBE0, with periodic code CRYSTAL14. First, the geometry optimization was performed using the analytical energy gradients, with respect to atomic coordinates and unit cell parameters. All-electron Gaussian basis sets were adopted for Titanium and Oxygen and for Rare-Earth atoms internal shells up to 4 f are replaced by the pseudopotentials. The results obtained are discussed and the agreement between the calculated values and experimental data are quite satisfactory.