Simulações por dinâmica molecular de compostos do tipo ABO3 (SrTiO3 e CaTiO3)

Abstract

Using the classical molecular dynamics simulations, Perovskites systems composed by oxides (ABO3), in particular SrTiO3 and CaTiO3, were performed. The titanates are easily prepared as polycrystalline ceramics; chemically and mechanically stable they can be characterized in various temperature and pressure conditions. These provide us reliable experimental results for construction and consolidation of theoretical models. Another important fact is that these materials have wide variety of technological applications and many important properties as well as the phase transitions arising from the effect of temperature and pressure. That can be explored to understand the interactions among its constituents. The effective interatomic potential used has the same functional form of the potential proposed by Vashishta and Rahman and it s composed by the sum of terms Coulomb interaction, van der Waals, esthereometric and dipole-induced. The system was treated in (N, V, E) and (N, P, H) ensembles to verify the influence of temperature and pressure application on structural and dynamics properties of perovskites. The method used allowed us to describe various properties such as thermal expansion coefficient, angles distribution, coordination number, elastic properties, pair distribution function, density of vibrational states, Debye-Waller factor and so on. The phase transitions of systems were explored showing fantastic results.