摘要
基于第一性原理的赝势平面波方法计算了完整YTaO_4和LuTaO_4晶体的电子结构、介电函数、折射率、吸收光谱。计算结果表明,二者价带的贡献都主要来源于O2p态。导带分为两部分,下导带都主要由Ta5d态组成,YTaO_4上导带主要由Y4d态组成。而LuTaO_4上导带的贡献主要来源于Lu5d态。在ω=0时,YTaO_4和LuTaO_4晶体的介电常数和折射率都非常接近;介电函数虚部的低能特征峰(小于10.0 eV)归因于TaO_4^(3-)基团的电子跃迁,对应电子从O2p价带到Ta5d导带的跃迁;10.0～15.0 eV之间的特征峰对应于电子从价带到上导带的跃迁;大于15.0 eV的特征峰则归因于O2s态的内层电子到导带的跃迁。两种晶体在紫外区的吸收带宽而强,此吸收带归属于从氧(2p)到钽d^0离子的电荷转移跃迁。
Electronic structures, dielectric functions, refraction indices, absorption spectra of perfect YTaO4 and LuTaO4 crystals are calculated using pseudo-potentials and plane waves based on first-principles method. The results show that valence bands of YTaO4 and LuTaO4 are both from O2p states. Conduction band is divided into two parts. The lower conduction band is mainly composed of Ta5d states and the upper conduction band involves contribution mainly from Y4d states of YTaO4 and Lu5d states of LuTaO4. When w equals to zero, the dielectric constants and refractive indices between YTaO4 and LuTaO4 are close to each other. The low-energy characteristic peaks below 10.0 eV of their imaginary parts originate from the electron transition within TaO4^3- complex. The low-energy characteristic peaks between 10.0 eV and 15.0 eV correspond to the electron transition from valence band to the upper conduction band. The peaks beyond 15.0 eV are due to the electron transition from O2s to conduction band. Last but not the least, the ultraviolet absorption bands of YTaO4 and LuTaO4 are broad and strong. They correspond to the charge transfer transition from oxygen （2p） to d^0 ion of tantalum.
出处
《光学学报》
EI
CAS
CSCD
北大核心
2009年第2期448-453,共6页
Acta Optica Sinica
基金
国家自然科学基金(50672068)
上海市科学技术委员会(05ZR14123
07DZ22302)资助课题
关键词
线性光学
电子结构
第一性原理计算
光学性质
linear optics
electronic structure
first-principle calculation
optical properties
