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弹性常数是矿物最重要的物性参数之一,它能为矿物结构的稳定性研究提供很有价值的信息,了解弹性性质与压力之间的关系是认识地球内部动力学过程及性质的基础.本文采用密度泛函理论中的PBEsol泛函对HgS同质异象体高压下的结构、弹性性质(弹性常数、零压下的体积模量及其一阶偏导)进行了研究,分析了HgS的弹性模量和焓随压强的变化情况,并据此得到相变压强.研究表明,β-HgS在约2.2~2.5 GPa时相变为α-HgS,随着压强进一步增加,α-HgS大概在12~21 GPa逐渐从辰砂结构转变为岩盐结构.通过与前人的研究结果对比发现,采用PBEsol得到的HgS晶格参数与实验值更接近,优于前人基于PBE计算的结果,但是本文基于PBEsol和前人基于PBE计算的弹性常数C_(ij),体积模量和焓与实验都存在不同程度的偏差,并且这两种泛函计算的结果之间也存在差异,这说明在实际应用中,对无法通过实验获得的高压弹性性质,最好选择不同泛函理论计算弹性常数C_(ij)、体积模量和焓并慎重分析.
The elastic constant is one of the most important physical parameters of minerals, which can provide valuable information for studying the stability of mineral structures. Understanding the relationship between elastic properties and stress is the basis for understanding the dynamical processes and properties of the earth. The structure, elastic properties (elastic constants, bulk modulus at zero pressure and first-order partial derivative) of HgS isomorphism were investigated by PBEsol functional theory of density functional theory. The effects of HgS Elastic modulus and enthalpy with pressure, and the phase transition pressure was obtained.The results show that β-HgS phase changes to α-HgS at about 2.2 ~ 2.5 GPa, and with the pressure increasing, α-HgS is about 12 ~ 21 GPa gradually changed from cinnabar structure to rock salt structure.Comparing with previous studies, it is found that the lattice parameter of HgS obtained by PBEsol is closer to the experimental value than the previous one based on PBE calculation, but based on the results of PBE calculation, PBEsol and the predecessors based on PBE calculated the elastic constants C_ (ij), the bulk modulus and enthalpy and the experiment there are varying degrees of deviation, and the results of these two functional calculations are also different, indicating that in practical applications , Unable to pass the real High pressure obtained by the elastic properties, the best choice for different functional theory calculated elastic constant C_ (ij), bulk modulus and enthalpy and carefully analyzed.