First Principles Study on Electronic Structure of PbFe_0.5Nb_0.5O₃

The full potential linearized augmented plane wave (FLAPW) method is used to study the crystal structure and electronic structure properties of PbFe_0.5Nb_0.5O₃ (PFN). The optimized crystal structure, density of states, band structure and electron density distribution have been obtained to understand the ferroelectric behaviour of PFN. The analysis result of the density of states shows there is an obvious change of Nbd states in the paraelectric-to-ferroelectric phase transition. The polarization result shows that the contribution to ferroelectricity of Nb atoms is larger than that of Fe atoms. In ferroelectric phase there is a hybridization of Fed--Op and Nbd--Op in ferroelectric PFN. This is consistent with the result of the electronic band structure. This hybridization is responsible for the tendency to its ferroelectricity.