First principles calculation on structural and lattice dynamic of SnTiO3 and SnZrO3

The geometry optimization, density of state (DOS) and lattice dynamic (born effective charges (BEC) and phonon dispersion) of SnTiO3 (STO) and SnZrO3 (SZO) cubic are investigated via first-principles computational methods. The results of DOS show that effect of different B-site cation–(Ti 3d, Zr 4d) states play an important role in chemical interaction particularly in changing of covalency between O2p and cation Sn-5p in STO and SZO, respectively. The BEC calculation shows the anomalous contribution to the Sn charge for both compound STO and SZO beyond the nominal charge of +2. Moreover, the replacement of Ti in STO by Zr strongly modifies the B–O interaction, suppressing the involvement change in nature of the unstable modes of SnZrO3. The results were compared and showed in good agreement with other calculated values using different methods.