In this paper, we present and discuss the results of first-principles calculations of the structural, electronic, optical, elastic and thermodynamic properties of the monoclinic quaternary nitride Ba₃Ca₂Si₂N₆. A comparison between the computed crystal structure parameters and the corresponding experimental counterparts shows a very good agreement between them. The elastic constants were evaluated numerically for the monocrystalline and polycrystalline Ba₃Ca₂Si₂N₆ using the strain–stress approach. The predicted elastic constants demonstrate that Ba₃Ca₂Si₂N₆ is soft, ductile and mechanically stable. Ba₃Ca₂Si₂N₆ shows a strong anisotropic behavior of the elastic and structural properties. The calculated band structure reveals a semiconductor character of Ba₃Ca₂Si₂N₆. The spectra of the macroscopic linear optical functions, namely the complex dielectric function, reflection coefficient, energy loss of electrons, absorption coefficient and complex refractive index, were calculated and discussed. The quasi-harmonic Debye model was used to explore the temperature and pressure dependencies of certain macroscopic physical parameters for Ba₃Ca₂Si₂N₆.

在本文中，我们介绍并讨论了单斜氮化季铵Ba ₃ Ca ₂ Si ₂ N ₆的结构，电子，光学，弹性和热力学性质的第一性原理计算结果。计算出的晶体结构参数和相应的实验参数之间的比较表明它们之间有很好的一致性。使用应变应力法，对单晶和多晶Ba ₃ Ca ₂ Si ₂ N ₆的弹性常数进行了数值评估。预测的弹性常数表明Ba ₃ Ca ₂ Si ₂ N₆是柔软，易延展和机械稳定的。Ba ₃ Ca ₂ Si ₂ N ₆具有强的各向异性，具有弹性和结构特性。计算出的能带结构揭示了Ba ₃ Ca ₂ Si ₂ N ₆的半导体特性。计算并讨论了宏观线性光学函数的光谱，即复介电函数，反射系数，电子能量损失，吸收系数和复折射率。使用准谐波德拜模型研究Ba ₃ Ca某些宏观物理参数的温度和压力依赖性₂ Si ₂ N ₆。