Theoretical study of the electronic structure, chemical bonding and optical properties of KNbO3 in the paraelectric cubic phase
Theoretical study of the electronic structure, chemical bonding and optical properties of KNbO3 in the paraelectric cubic phase
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DOI：
10.1088/0953-8984/15/35/304
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发表时间：
2003-09-10
影响因子：
2.7
通讯作者：
Okoye, CMI
中科院分区：
文献类型：
--
作者：
Okoye, CMI
采用全势线性缀加平面波方法，在广义梯度交换和关联近似下，研究了顺电立方相KNbO_3的电子能带结构、态密度和电荷密度轮廓.能带结构显示出间接（R-γ）带隙。从DOS分析以及电荷密度的研究，我们发现，K和NbO_3之间的键主要是离子，而Nb和O之间的共价键。我们还报道了这种化合物的能隙的压力变化的结果，并发现，随着压力的增加，带隙增加。为了了解钙钛矿的光学性质，计算了介电函数、反射率、吸收系数、光学电导率、电子能量损失函数、折射率和消光系数的真实的和虚部。分析了光谱的一般轮廓，并讨论了结构的起源。
The electronic energy band structure, density of states (DOS) and charge density contour of KNbO3 in the paraelectric cubic phase have been studied using the full-potential linearized augmented plane wave method within the generalized gradient approximation for exchange and correlation. The band structure shows an indirect (R-Gamma) band gap. From the DOS analysis as well as charge density studies, we find that the bonding between K and NbO3 is mainly ionic while that between Nb and O is covalent. We have also reported results on the pressure variation of the energy gap of this compound and found that the band gap increases with increasing pressure. In order to understand the optical properties of the perovskite, the real and imaginary parts of the dielectric function, reflectivity, absorption coefficient, optical conductivity, electron energy-loss function, refractive index and extinction coefficient were calculated. The general profiles of the optical spectra were analysed and origins of the structures discussed.