Ge2 Sb2 Te5晶体结构的第一性原理模拟

摘要

This paper optimized the structure of the metastable face centered cubic Ge2 Sb2 Te5 using the software CASTEP based on the density functional theory method. The numerical models were established by the local density function LDA CA-PZ and the generalized gradient approximation GGA PBE, and the effects of the two methods on the band, density of states, partial density of states, electron density, and other related properties were further compared and analyzed. The properties of the structure were obtained. Results showed that the structure of Ge2 Sb2 Te5 calculated by LDA CA-PZ had lower energy and better stability than that simulated by using GGA PBE. However, the lattice constant calculated by GGA PBE agreed well with experimental results while it was narrowing calculated by LDA CA-PZ. The metastable Ge2 Sb2 Te5 presented the typical metallic properties with no band gap while the greatest impact on the material properties was Te atoms.%基于密度泛函理论，采用CASTEP软件对Ge2 Sb2 Te5亚稳态晶体进行结构优化，并比较了局部密度泛函LDA CA-PZ和广义梯度近似GGA PBE两种不同电子交换关联函数对模型晶体结构、能带、态密度、分波态密度、布居数等相关性质的影响，获得Ge2 Sb2 Te5亚稳态晶体结构的性质。研究发现，电子交互关联函数采用局部密度泛函LDA CA-PZ时计算体系的总能量更低，具有更好的稳定性，但该优化使晶格常数缩小，而采用广义梯度近似GGA PBE方法对GST材料的晶胞结构进行模拟获得的结果与实验结果较为吻合。亚稳态Ge2 Sb2 Te5的能带没有带隙，呈现典型的金属性，而对材料性质影响最大的是Te原子。