Estructura electrónica y origen de la ferroelectricidad en el Bi$_{4}$Ti$_{3}$O$_{12}$, por medio de cálculos de primeros principios

Abstract

Using the full-potential augmented plane-wave method (LAPW-method), theoretical results on the electronic structure and ferroelectric instabilities in the structure of Bi$_{4}$Ti$_{3}$O$_{12 }$are presented here. The equilibrium coordinates of all the atoms in the tetragonal phase (paraelectric) were calculated. Using the frozen phonon method, it was found that in the considered crystalline structure there are two unstable phonon modes with different displacement patterns, which explain at least partially the primary source for ferroelectricity in the studied compound. Besides, the band structure, the total and site-projected electronic densities of states for the valence and conduction bands of Bi$_{4}$Ti$_{3}$O$_{12 }$are reported, which allowed us to understand the electronic origin of the ferroelectric instabilities.