中文摘要：

通过Ca替换CaCu3TiaO12晶胞中的所有Cu，建立了包含Ti08八面体扭转的CaTi03；通过Cu替换CaTi032×2×2超胞中3／4的Ca，建立了不包含Cu04正方形的CaCu3Ti4O12。采用Materials Studio软件的CASTEP模块，对比了上述晶体和标准晶体成键状况、能带结构、态密度及介电函数，分析了Ti06八面体扭转和Cu04正方形的影响，发现了Cu-O键或CuO4正方形对CaCu3Ti4O12光频介电常数的关键性作用。研究结果提供了通过内禀机制优化CaCu3Ti4O12材料介电性能的新途径。

英文摘要：

In order to reveal the influence of twisted TiO6 octahedrons and CuO4 squares on dielectric properties of Ca- Cus Ti4 O12, CaTiOs and CaCus Tia O1z were investigated comparatively by First principles. Based on the crystal cell of CaCus Ti4 Olz, CaTiOs crystal cell with twisted TiO6 octahedrons was built by substituting Ca for all the Cu atoms. Based on 2×2 ×2 supercell of CaTiOs, CaCusTi4Olz crystal cell without CuO4 squares was built by substituting Cu for 3/4 of the Ca atoms. CASTEP module in First principle calculation software of Materials Studio was used to investigate the difference in bonding, energy band structure, state density and dielectric function for the crystals mentioned above and normal CaTiOs and CaCus Ti4 O12 crystals. The influence of twis- ted TiO6 octahedrons and CuO4 squares for perovskite was analyzed. It was found that Cu-O bonds or CuO4 squares play a key role in optical frequency dielectric permittivity of CaCus Ti4 O12. The research of this paper offers a new route to optimize dielectric properties of CaCusTi4O12 by intrinsic mechanism.