Atomic Displacements in Perovskite Strontium Titanate



The relative atomic displacements of the sublattices of perovskite strontium titanate associated with optical frequency mode are calculated using all possible interionic couplings. The couplings are estimated from the observed optical frequencies of SrTiO3. The results of the calculation are plotted as a function of a parameter Φ(∼TTc). It is found that two sets of solutions exist which correspond to the proposals of SLATER and LAST.