固态二氧化碳电子结构及性能的理论研究

采用基于赝势平面波理论的第一性原理计算方法,研究了9种结构的固态二氧化碳的结构和性质.经过结构的几何优化,得到α石英稳定结构晶格常数与他人的计算值基本一致.通过对平衡态能量的分析,我们得出β方石英(cristobalite)结构是能量最低的结构.这与文献的研究结果一致.对弹性性质的计算结果表明,除了超石英(stishovite)和立方黄铁矿(cubic-pyrite)结构之外,其他的结构都是弹性稳定的.利用基于Mulliken轨道重叠布居数的共价固体本征硬度计算方法,预测了各个结构的本征硬度值.结果表明, 关键词： 第一性原理计算 固态二氧化碳 电子结构 硬度

Theoretical study on electronic structure and properties of solid carbon dioxide

We systematically investigate the equilibrium energy, the density of states, and the elastic property of solid CO₂ by the plane wave pseudo-potential method in the generalized gradient approximation and local density approximation based on the density function theory. The calculated lattice parameters of α-quartz are consistent with other calculation values. The equilibrium energy calculation indicates that β-cristobalite structure is more stable under the ambient condition, which is consistent with the results reported in other reffrences.The computation results of elastic constants show that they are elastically stable in structure exception for stishovite and cubic-pyrite. The hardness values for these structures are evaluated according to the intrinsic hardness calculation theory of covalent crystal based on the Mulliken overlap population. The results indicate that none of these phases are of superhard material. Furthermore, we clarify the stereochemical effect of the lone-pair electrons on the hardness of the solid CO₂.