| Summary: | 碩士 === 淡江大學 === 物理學系碩士班 === 98 === We used the first principles theory to calculate the dielectric properties of the materials. In first principle calculation, we used” density-functional perturbation theory” and “linear response method” to simplify the simulation process. We first used diamond as model materials to test the accuracy of calculation.
After verifying the feasibility of first principle calculation, we then proceeded to calculate the phonon characteristics at Γ-point of BaTiO3 and Ba(Zn1/3Nb2/3)O3 materials. We identified the vibrational characteristics at each modes, compared these vibrational characteristics with the measured Raman and FTIR spectroscopy, estimated their dielectric properties. We concluded that the dielectric constant of ABO3 materials is closely related to the tightness of the octahedron, whereas the quality factor is intimately related to the distortion of the octahedron.
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