铁基超导材料FeTe_(0.5)Se_(0.5)的第一性原理研究  

First-Principles Study of Iron-Based Superconducting Material FeTe_(0.5)Se_(0.5)

作　　者：李健[1] 茅伟华 黄桂芹[1] 

机构地区：[1]南京师范大学物理科学与技术学院,江苏南京210023 [2]江苏省吴江市青云实验中学,江苏吴江215235

出　　处：《南京师大学报（自然科学版）》2013年第1期43-47,共5页Journal of Nanjing Normal University(Natural Science Edition)

基　　金：国家自然科学基金(10947005)

摘　　要：采用第一性原理计算了FeTe0.5Se0.5在两种不同结构模型下的电子结构、晶格动力学以及电声子相互作用.结果表明:用两种结构模型计算得到的电子结构大致相同,费米面附近的态密度主要来自Fe d电子的贡献.对两种模型我们根据不可约表示分析了Γ点的光学模频率,并给出了声子谱及声子态密度.用模型1和模型2计算得到的电声子耦合常数λ分别为0.20和0.22,都非常弱,无法解释实验上较高的超导转变温度.因此,超导材料FeTe0.5Se0.5和其他的铁基超导材料一样,都不属于常规的电声子耦合超导材料.The electronic structure, lattice dynamics and electron-phonon interaction of FeTe0.5 Se0.5 in two different structural models are investigated by using the first-principles. The results show that the electronic structures of the two structural models are similar to each other,and the electronic density of states near the Fermi level comes mainly from Fed electrons. For both two models,we analyze the optical modes at the F point based on irreducible representation, and give the phonon spectra and the phonon density of the states. The electron-phonon coupling coefficients A calculated by model 1 and model 2 are 0. 20 and 0.22, respectively, which are both too small to explain the high superconducting transition temperature discovered in experiment. Therefore,we think that superconducting material FeTe0.5 Se0.5 doesn＇t belong to the conventional electron-phonon coupling mechanism,which is similar to the other Fe-based superconducting materials.

关 键 词：铁基超导 晶格动力学 电声子相互作用 第一性原理 

分 类 号：O511.4[理学—低温物理]