四方相BaTiO3铁电性的第一性原理研究

在广义梯度近似下，利用超软赝势对立方相和四方相BaTiO3晶胞中Ti原子沿c轴位移时体系的能量、原子间电子云重叠布局数和各原子上的净电荷等进行了自洽计算.结果显示，当Ti原子沿c轴位移0012nm时，四方相BaTiO3体系能量最低，其自发极化强度为0261C/m2，该结果与实验数据相符合；同时表明，O原子的2p轨道和Ti原子的3d轨道的杂 化是BaTiO3晶体出现铁电性的重要原因. 关键词： 四方相BaTiO3 铁电性 位移 态密度

First-principles study on tetragonal BaTiO3 ferroelectric

Based on the generalized gradient approximation (GGA), the total-energy, overla p populations and valence charges in the case of Ti atoms moving along c axis in cubic and tetragonal phases were calculated by using ultrasoft pseudopotentials ( USP) plane wave method. It was demonstrated that the energy of tetragonal BaTiO 3 was the lowest when Ti atoms move along the c axis by up to 0.012nm, an d t he sponta neous polarization was 0.261C/m2 , which was consistent with experimental res ult s. Moreover, it was also confirmed that the ferroelectric stability of BaTiO 3 could be attributed to the orbital hybridization of 2p orbit of oxygen atom and 3d orbit of Ti atom.