Abstract Employing the Projector Augmented Wave (PAW) and all-electron Full-Potential Linealized Augmented Plane-Wave (FP-LAPW) methods with the Generalized Gradient Approximation (GGA), we have investigated the electronic band structure (EBS) and densities of states (DOS) of YGa2, crystallizing in the hexagonal AlB2-type structure with space group P6/mmm. Further, we have evaluated for the first time dielectric and optical properties of this compound. Noticeable anisotropy in YGa2 has been observed in the frequency-dependent dielectric functions and other optical quantities for the photon waves polarized along the c and ab-plane. On the basis of a comparison of EBS, DOS and frequency dependencies of optical quantities, we have interpreted the spectrum structures as the results of the intraband and interband transitions for energies below 15 eV and the core level excitations for energies beyond 22 eV. We have found several similarities of the optical properties to those of superconducting MgB2 but clear distinctions to those of nonsuperconducting AlB2.

中文翻译：

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YGa2电子结构和光学性质的密度泛函理论研究

摘要 利用投影仪增强波 (PAW) 和全电子全电位线性增强平面波 (FP-LAPW) 方法和广义梯度近似 (GGA)，我们研究了电子能带结构 (EBS) 和态密度(DOS) YGa2，在空间群为 P6/mmm 的六角形 AlB2 型结构中结晶。此外，我们首次评估了该化合物的介电和光学特性。在沿 c 和 ab 平面极化的光子波的频率相关介电函数和其他光学量中，已经观察到 YGa2 中明显的各向异性。在比较 EBS、DOS 和光量的频率依赖性的基础上，我们已经将光谱结构解释为能量低于 15 eV 的带内和带间跃迁以及能量超过 22 eV 的核心能级激发的结果。我们发现光学性质与超导 MgB2 的光学性质有几个相似之处，但与非超导 AlB2 的光学性质有明显区别。