Abstract

Optical properties of titanium dichalcogenide compounds, TiX₂ (X = S, Se, and Te) have been calculated by first-principles calculations using density functional theory as implemented in SIESTA code. The unit cell of each of these compounds was optimized and the calculations were performed to obtain the optical properties. Further, external electric field (along Z direction) and biaxial strain (along X and Y directions) was employed to study their effect on these properties. The effect of biaxial strain on the geometry of the compounds is also studied. The optical properties are investigated for polarized light along the Z direction (c axis). This include the calculation of real and imaginary parts of dielectric function, absorption coefficient, reflectance, optical conductivity, and refractive index in 0–25 eV energy range. Various modulations of these properties are observed including the blue shifts and red shifts of energies with highest peaks in the visible region and also shifting of energies to other regions of the electromagnetic spectrum. Hence, due to the tunable diverse optical properties, the compounds can be useful in the field of optoelectronics and in making various optical devices.

中文翻译：

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外加电场和应变作用下TiX 2（X = S，Se和Te）化合物光学性质的第一性原理研究

摘要

二硫化钛钛化合物TiX ₂（X = S，Se和Te）的光学性质已通过使用SIESTA代码实现的密度泛函理论通过第一原理计算得出。对这些化合物中每一种的晶胞进行了优化，并进行了计算以获得光学性质。此外，采用外部电场（沿Z方向）和双轴应变（沿X和Y方向）来研究它们对这些特性的影响。还研究了双轴应变对化合物几何形状的影响。研究了沿Z方向（c轴）。这包括计算介电函数的实部和虚部，吸收系数，反射率，光导率和0-25 eV能量范围内的折射率。观察到这些性质的各种调制，包括在可见光区域具有最高峰值的能量的蓝移和红移，以及能量向电磁谱的其他区域的转移。因此，由于可调谐的多样的光学特性，这些化合物可用于光电子学领域以及制造各种光学器件。