First principles study of structural and vibrational properties of (B = Mg, Zn) in cubic and tetragonal phases

摘要

The structural and vibrational properties of Sr_2MgWO_6 and Sr_2ZnWO_6 double perovskites in the space group Fm3m (cubic) and I4/m (tetragonal) have been investigated using the pseudopotential plane wave method based on density functional theory (DFT) under local density approximation (LDA) and generalized gradient approximation (GGA). The structural parameters along with the Raman and infrared wavenumbers at zone center are calculated. The calculated values of lattice constants and Raman wavenumbers are in very good agreement with the experimental values for both cubic and tetragonal phases.