First principles study of structural and vibrational properties of Ba2YTaO6 in cubic and tetragonal phases

The structural and vibrational properties of Ba2YTaO6 type double perovskites in the space group Fm (3) over barm (cubic) and I4/m (tetragonal) have been investigated for the first time using the pseudopotential plane wave method based on density functional theory (DFT) under local density approximation (LDA) and linear response formalism. The lattice constants along with the Raman and infrared wavenumbers at zone center are calculated and assigned. The calculated values of lattice constants and Raman and infrared wavenumbers are in very good agreement with the experimental values for both cubic and tetragonal phases. The value of the E-g mode has been reassigned on the basis of present calculation. Assignment of modes has been done for the first time in tetragonal structure. (C) 2012 Elsevier B.V. All rights reserved.