Structure and Lattice Dynamics of Nd2TiO5 and Sm2TiO5 Crystals: Ab Initio Calculation

Abstract

Ab initio study of the crystalline structure and the phonon spectrum of R₂TiO₅ (R = Nd, Sm) crystals is conducted using the density functional theory. The calculations are carried out using the hybrid functional, which takes into account the contribution of nonlocal exchange to the Hartree–Fock formalism. Coordinates of ions in the unit cell and lattice constants, as well as frequencies and types of fundamental vibrations, intensities of lines of Raman and IR reflectance spectra are determined. The elastic constants of R₂TiO₅ are calculated for the first time.