In recent years, some laboratories have been able to prepare calcium hydrobromide (CaHBr) by melting hydride and anhydrous bromide or metal and bromide in a hydrogen atmosphere at 900°C and have studied some of its properties. But there are few theoretical studies, especially the theoretical studies of monolayer CaHBr. We use the first-principles method to calculate the structure, elastic properties, and lattice thermal conductivity of the monolayer CaHBr based on the Boltzmann transport equation. We obtain a stable crystal structure by the optimization of monolayer CaHBr. By calculating the elastic constant of monolayer CaHBr, its mechanical stability is proved, and the elastic limit of monolayer CaHBr is obtained by biaxial tensile strain on monolayer CaHBr. And the corresponding phonon spectra show no imaginary frequency, indicating the dynamic stability of the monolayer CaHBr. By the ShengBTE code, we calculate the lattice thermal conductivity of the monolayer CaHBr, the iterative solution of BTE and RTA at 300 K–1200 K is obtained, and the lattice thermal conductivity at room temperature is and , respectively. It can be seen that the lattice thermal conductivity of monolayer CaHBr is low. And by analyzing the phonon spectrum, the scattering rate, and the mean free path of the phonons, the lattice thermal conductivity of monolayer CaHBr mainly depends on the acoustic modes. We hope this study can provide theoretical guidance for the experiments and practical application of monolayer CaHBr.

中文翻译：

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单层氢溴酸钙的结构，弹性和导热性的第一性原理研究

近年来，一些实验室已经能够通过在900°C的氢气氛围中将氢化物和无水溴化物或金属和溴化物熔融来制备氢溴化钙（CaHBr），并研究了其某些性能。但是很少有理论研究，特别是单层CaHBr的理论研究。我们使用第一原理方法根据玻尔兹曼输运方程计算单层CaHBr的结构，弹性性质和晶格热导率。我们通过优化单层CaHBr获得了稳定的晶体结构。通过计算单层CaHBr的弹性常数，证明了其机械稳定性，并通过对单层CaHBr的双轴拉伸应变获得了单层CaHBr的弹性极限。并且相应的声子谱没有虚频，表明单层CaHBr的动态稳定性。通过ShengBTE代码，我们计算出单层CaHBr的晶格热导率，得到了BTE和RTA在300 K–1200 K下的迭代解，室温下的晶格热导率为 和 ，分别。可以看出，单层CaHBr的晶格热导率低。通过分析声子的光谱，声子的散射速率和平均自由程，单层CaHBr的晶格热导率主要取决于声模。我们希望这项研究能够为单层CaHBr的实验和实际应用提供理论指导。