近代固態物理的發展配合高速電腦的理論計算，已成為我們研究各式新穎樣品的重要途徑，本研究即以第一原理模擬計算微波介電材料(1-x)La2/3TiO3-xLaAlO3。首先我們從0.9La2/3TiO3 -0.1 LaAlO3的晶格結構中獲得純La2/3TiO3的原子位置，接著以密度泛函微擾理論來研究該材料在Γ點上之聲子行為。從聲子的計算結果輔以實驗量測獲得的拉曼光譜與紅外光光譜，藉此探討微觀下的聲子振動行為與介電機制的關係。 At the present, the combination of high performance computation and solid-state theory provides a promising methodology to elucidate the microscopic properties of versatile materials. We use the first-principles to start the simulation on the microwave dielectric material La2/3TiO3 - LaAlO3. At first, we get the La2/3TiO3 crystal structure from the atomic position of ceramic 0.9La2/3TiO3-0.1LaAlO3 , and then we use the Density - Functional Perturbation Theory to investigate the phonons at Γ point. According to the phonon calculation, the calculated eigenvalues and the corresponding eigenvectors of each vibrational mode at Γ point provide a great help on our experimental observations. Comparing with Raman and FTIR spectrum, we can study the dielectric properties on the microwave dielectric material La2/3TiO3 - LaAlO3.
