Rusevich Leonid L, Brik Mikhail G, Gryaznov Denis, Srivastava Alok M, Chervyakov Ilya D, Zvejnieks Guntars, Bocharov Dmitry, Kotomin Eugene A
Institute of Solid State Physics, University of Latvia, 8 Kengaraga Str., LV-1063 Riga, Latvia.
School of Optoelectronic Engineering & CQUPT-BUL Innovation Institute, Chongqing University of Posts and Telecommunications, Chongqing 400065, China.
Materials (Basel). 2025 Apr 29;18(9):2025. doi: 10.3390/ma18092025.
Cesium hexafluorosilicate (CsSiF, CSF) and potassium hexafluorosilicate (KSiF, KSF) compounds are suitable hosts for luminescent impurities. In this work, the results of first-principle calculations of the basic properties of both these compounds are discussed and compared with the available experimental and theoretical data. The simulations were performed using the CRYSTAL23 computer code within the linear combination of atomic orbitals (LCAO) method of the density functional theory (DFT) and the advanced hybrid DFT-HF exchange-correlation B1WC functional. A comparative study of the structural, electronic, and elastic properties of the two materials is presented, along with a study of the dependence of properties on external pressure in the range of 0-20 GPa. In particular, the electronic properties with an emphasis on the effective atomic charges (by means of Mulliken analysis) and the chemical bonding properties (by means of crystal orbital overlap population (COOP) analysis) were addressed, with regards to the pressure effects. The structure of the valence bands at 0 and 20 GPa was compared. The vibrational properties of CSF and KSF were calculated, including the simulation of the one-phonon IR and Raman spectra. The calculated Raman spectra exhibit excellent agreement with the experimental ones. The pressure dependences of sound speeds and the Debye temperature are evaluated.
六氟硅酸铯（CsSiF₆，CSF）和六氟硅酸钾（K₂SiF₆，KSF）化合物是发光杂质的合适基质。在这项工作中，讨论了这两种化合物基本性质的第一性原理计算结果，并与现有的实验和理论数据进行了比较。使用CRYSTAL23计算机代码，在密度泛函理论（DFT）的原子轨道线性组合（LCAO）方法和先进的杂化DFT-HF交换关联B1WC泛函下进行了模拟。对这两种材料的结构、电子和弹性性质进行了比较研究，并研究了在0-20 GPa范围内性质对外部压力的依赖性。特别地，针对压力效应，研究了电子性质，重点是有效原子电荷（通过Mulliken分析）和化学键性质（通过晶体轨道重叠布居（COOP）分析）。比较了0和20 GPa下价带的结构。计算了CSF和KSF的振动性质，包括单声子红外和拉曼光谱的模拟。计算得到的拉曼光谱与实验光谱表现出极好的一致性。评估了声速和德拜温度的压力依赖性。
