Research with KNbO₃ Bulk and Surface Properties Based on Density Functional Theory

The geometrical structure optimization, band structure, density of states, and charge density contour of potassium niobate (KNbO₃) in the bulk 100 direction and (100) surface are calculated and analyzed using density functional theory. The elastic constants, which can describe the bonding characteristics and structural stability, are also computed, and the dielectric function, which can be used to calculate all the other optical properties of the material, is evaluated. Local density approximation functional analysis using CASTEP software is also employed. Several similarities and differences are observed in the properties of the KNbO₃ bulk and surface. Almost all of the calculated results for the bulk sample are twice those of the surface sample. The results are consistent with the experiment.