Ground state and lattice dynamical study of ionic conductors CaF 2, SrF 2 and BaF 2 using density functional theory

Abstract

The present paper reports a comprehensive and complementary study on structural, electronic and phonon properties of face centered cubic fluorites, namely CaF 2, BaF 2 and SrF 2, using first principles density functional calculations within the generalized gradient approximation. The calculated lattice constants and bulk modulus are in good agreement with available experimental data. The analysis of band structure and density of states confirms the ionic character for all the three fluorides. The phonon dispersion curves and corresponding phonon density of states obtained in the present work are consistent with the available experimental and other theoretical data. The LO–TO splitting is maximum for CaF 2, which confirms that the ionicity is maximum in the case of CaF 2. The phonon properties for SrF 2 have been calculated for the first time.