Using first-principles calculations, we have investigated the structural, electronic, optical, thermodynamic and vibrational properties of Thorium disulfide (ThS 2 ) in Pnma symmetry. Structural properties are explored using CASTEP simulation code along with Generalized Gradient Approximation. Values of lattice parameters ( a = 7.27 Å, b = 4.33 Å and c = 8.56 Å) determined in the present work are found in good agreement with the former studies. After geometry optimization of the crystal structure of ThS 2 , electronic properties containing the electronic band structure, total density of states and partial density of states have been investigated. ThS 2 shows direct energy band gap of 0.995 eV, thus, it belongs to semiconducting materials. Optical analysis discloses that maximum absorption occurs in the UV range of the electromagnetic spectrum. Vibrational properties investigated through density functional perturbation theory depict no imaginary or negative frequencies in the phonon spectrum, leading to its dynamical stability. A low frequency optical mode of vibration showing symmetric stretching has been noticed at 40.53 cm −1 frequency. In order to seek thermo-dynamical stability of thorium disulfide, thermodynamic properties were calculated using harmonic approximation, making thorium disulfide suitable for thermodynamic applications.

中文翻译：

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用于核燃料应用的 ThS2 的结构、电子、光学和振动行为的预测：DFT 研究

使用第一性原理计算，我们研究了 Pnma 对称性中二硫化钍 (ThS 2 ) 的结构、电子、光学、热力学和振动特性。使用 CASTEP 模拟代码和广义梯度近似来探索结构特性。在目前的工作中确定的晶格参数值 (a = 7.27 Å, b = 4.33 Å 和 c = 8.56 Å) 与以前的研究非常吻合。在对ThS 2 晶体结构进行几何优化后，研究了包含电子能带结构、总态密度和部分态密度的电子性质。ThS 2 的直接能带隙为0.995 eV，属于半导体材料。光学分析表明，最大吸收发生在电磁波谱的紫外范围内。通过密度泛函微扰理论研究的振动特性描述了声子谱中没有虚频或负频率，从而导致其动态稳定性。在 40.53 cm -1 频率处注意到显示对称拉伸的低频光学振动模式。为了寻求二硫化钍的热力学稳定性，使用调和近似计算热力学性质，使二硫化钍适合热力学应用。