插层化合物LixTiS2中Li离子-空位二维有序结构稳定性的第一性原理研究

根据局域密度近似下的密度泛函理论，用第一性原理方法对TiS₂，LiTiS₂和Li_xTiS₂(x=1/4, 1/3, 1/2, 2/3, 3/4)有序系统进行了几何优化和总能量计算.将计算结果与已有的实验和理论结果进行了对比，得到的归一化结构参量增量Δa₀和Δc₀随离子浓度单调地增加，与实验结果符合较好.Li_{关键词： x}TiS₂')" href="#">Li_xTiS₂ 有序结构 第一性原理计算 密度泛函理论

First principles computational study on the stability of Li ion-vacancy two-dimensional ordered structures in intercalation compounds LixTiS2

Geometry optimization and total energy computation were carried out for TiS₂, LiTiS₂ and intercalation compound Li_xTiS₂(x=1/4, 1/3, 1/2, 2/3, 3/4)ordered systems using first principles method based on local density approximation to density-functional theory. The computation results for these systems have been compared with other experimental and theoretical results available in the literature. The normalized increments of lattice parameters Δa₀ and Δc₀ increase monotonicly with the increasing concentration of Li ion. The curves show good agreement with lattice parameters obtained from experiment. The formation energies of ordered systems Li_xTiS₂(x=1/4, 1/3, 1/2, 2/3, 3/4) are all negative, indicating their stability at low temperature. The formation energy of Li_1/2TiS₂ system with 3a₀×a₀ ordered structure is the lowest, implying the most stable structure. The results have shows that the local density approximation to density-functional theory can reasonably be applied to TiS₂, LiTiS₂ and intercalation compound Li_xTiS₂(x=1/4, 1/3, 1/2, 2/3, 3/4)ordered systems.