Abstract LiZnPS4 is thought to be a promising mid-infrared optical crystal and lithium battery material, but its fundamental properties are still not well investigated. In this work, we performed a systematic study on its electronic, elastic, infrared and electrical properties. The results indicate that LiZnPS4 is an indirect band gap crystal. Calculated partial density of states reveals that the top of its valence band is formed by the S 3p orbital while the component of the bottom of the conduction band is complex. The Zn 4p orbital is not empty in LiZnPS4 owing to the tetrahedral coordination of the Zn atoms. Calculated elastic properties indicate that LiZnPS4 is a mechanically stable crystal with elastic anisotropy. It has a relatively low Debye temperature of 294.8 K. Its infrared absorption spectrum was simulated and the origins of the strong peaks in it were revealed. Vibrational modes at the Brillouin zone center were illustrated and Born effective charges were calculated and discussed. Computed dielectric constants uncover that electrons contribute more to the total dielectric constants than ions. Studies imply that LiZnPS4–Li+ battery has a high theoretical voltage, a low electric capacity and a slightly high activation barrier.

中文翻译：

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LiZnPS4 电子、弹性、红外和电学性质的第一性原理研究

摘要 LiZnPS4 被认为是一种很有前途的中红外光学晶体和锂电池材料，但其基本性质仍未得到很好的研究。在这项工作中，我们对其电子、弹性、红外和电学特性进行了系统研究。结果表明，LiZnPS4 是一种间接带隙晶体。计算的部分态密度表明，其价带顶部由 S 3p 轨道形成，而导带底部的成分是复杂的。由于 Zn 原子的四面体配位，LiZnPS4 中的 Zn 4p 轨道不是空的。计算的弹性性能表明 LiZnPS4 是一种机械稳定的晶体，具有弹性各向异性。它的德拜温度相对较低，为 294.8 K。模拟了其红外吸收光谱，揭示了其中强峰的来源。说明了布里渊区中心的振动模式，并计算和讨论了玻恩有效电荷。计算出的介电常数表明电子比离子对总介电常数的贡献更大。研究表明，LiZnPS4–Li+ 电池具有较高的理论电压、较低的电容量和略高的活化势垒。