BiTiO3电子结构及光学性质的第一性原理研究∗

摘要

采用基于第一性原理的赝势平面波方法,对BiTiO3的多种结构进行了计算.计算结果表明, C 1C 1结构最为稳定,对应晶格参数为a=b=5.606Å, c=9.954Å；α=β=105.1◦,γ=61.2◦.进一步对C 1C 1结构的BiTiO3的能带结构、电子性质和光学性质进行了研究,发现BiTiO3是间接带隙半导体,其费米面附近的能带主要由Ti-3d和O-2p层的电子态构成.通过介电函数、复折射率和反射率等的研究,发现BiTiO3的光学性质为近各向同性.%BiTiO3 of C1C1 structure is found to be the most stable phase according to our first-principles calculations for nine possible structures, with corresponding optimized crystal parameters of a=b=5.606 Å, c=9.954 Å; α=β =105.1◦,γ =61.2◦. Subsequently, we have investigated the electronic and optical properties of BiTiO3 in C1C1 structure. It is found that BiTiO3 is a semiconductor with an indirect band gap with its energy band near Fermi level being dominated by O-2p and Ti-3d levels. Additionally, the dielectric function, refractive index, and reflectivity of BiTiO3 are also calculated, and it is shown that the optical properties of BiTiO3 are nearly isotropic.