Zinc blende (zb) and wurtzite (wz) structure of cadmium sulfide (CdS) are analyzed using density functional theory within local density approximation (LDA), generalized gradient approximation (GGA), Hubbard correction (GGA + U), and hybrid functional approximation (PBE0 or HSE06). To assure the accuracy of calculation, the convergence test of total energy with respect to energy cutoff and k-point sampling is performed. The relaxed atomic position for the CdS in zb and wz structure is obtained by using total energy and force minimization method following the Hellmann–Feynman approach. The structural optimization and electronic band structure properties of CdS are investigated. Analysis of the results shows that LDA and GGA underestimate the bandgap due to their poor approximation of exchange-correlation functional. However, the Hubbard correction to GGA and the hybrid functional approximation give a good bandgap value which is comparable to the experimental result. Moreover, the optical properties such as real and imaginary parts of the dielectric function, the absorption coefficient, and the energy loss function of CdS are determined.

中文翻译：

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使用密度泛函理论研究闪锌矿和纤锌矿硫化镉 (CdS) 的电子、结构和光学特性

使用密度泛函理论在局部密度近似 (LDA)、广义梯度近似 (GGA)、哈伯德校正 (GGA + U) 和混合函数近似中分析硫化镉 (CdS) 的闪锌矿 (zb) 和纤锌矿 (wz) 结构（PBE0 或 HSE06）。为了保证计算的准确性，对能量截止和k点采样进行了总能量的收敛测试。通过使用遵循 Hellmann-Feynman 方法的总能量和力最小化方法，获得 zb 和 wz 结构中 CdS 的松弛原子位置。研究了CdS的结构优化和电子能带结构特性。结果分析表明，LDA 和 GGA 低估了带隙，因为它们对交换相关函数的近似性较差。然而，对 GGA 的哈伯德校正和混合函数近似给出了与实验结果相当的良好带隙值。此外，还确定了介电函数的实部和虚部、吸收系数和 CdS 的能量损失函数等光学特性。