Study of the feature of lattice dynamic and ferroelectric transition in perovskites using molecular-dynamics modeling

摘要

Static and dynamic correlation functions of the BaTiO(3) crystal are calculated using molecular-dynamics (MD) modeling. Based on time-dependent pair correlation functions, phonon spectra of BaTiO(3) are calculated and the central peak of inelastic scattering is studied. It is shown that the phonon frequencies calculated by the MD method are in quite good agreement with those we obtained previously in the quasiharmonic approximation [1, 2]. It is demonstrated that the central peak of inelastic scattering is mainly associated with the soft optical mode and has the same symmetry. The coincidence of symmetries makes it possible to explain both the features in the X-ray scattering and the EXAFS spectroscopy.