NbP型Weyl半金属的力学和电子特性研究
毕业论文关键词：密度泛函理论 NbP Weyl 半金属 弹性常数 态密度
The Research on Mechanical and Electronic Properties of the Weyl Semimetal NbP
Abstract The research on topological insulator in the material science has made a great progress. It has made people start to ponder over whether the metal can also be pided into ordinary metal and topological metal .Along with the deep research on the topological metal, Weyl Semimetal has received wide attention because of its special physical characteristics. Based on pseudo potential plane wave method of density functional theory, it optimizes the structure of the Weyl Semimetal NbP which is in the Isomorphic family under different pressure, and it gets NbP Semimetal’s lattice constant. It discusses the mechanical and electronic properties of NbP Semimetal, calculates and analyses elastic constant、modulus of elasticity、anisotropy、 Debye temperature、 density of states and band structure. Results show that NbP Semimetal follows the standard of mechanical stability and shows anisotropic properties. It is found that the density of states on the fermi surface equal to zero, which is the characteristic of semimetal This paper has 5 figures, 10 tables and 33 references.
Key Words: density functional theory NbP Weyl semimetal elastic constant density of states
目录
摘要I
Abstract.II
目录.III
图清单.IV
表清单.IV
变量注释表V
1绪论1
1.1NbP型Weyl半金属简介.1
1.2NbP型Weyl半金属的研究意义.1
1.3NbP型Weyl半金属的研究背景.2
1.4研究目的2
2理论基础4
2.1能带理论4
2.2密度泛函理论4
2.3弹性理论8
2.4软件介绍12
3NbP型Weyl半金属的力学和电子特性的理论计算14
3.1软件计算参数选择14
3.2晶体结构分析14
3.3NbP晶体的力学特性15
3.4NbP晶体的电子特性19
4总结.22
参考文献.23
致谢.25
1 绪论 1.1 NbP 型 Weyl 半金属简介 近代凝聚态物理是在能带理论的基础上发展起来的，能带理论的内容就是在晶体的微观结构中，电子在周期性的固体中呈现能带结构[1]。根据泡利不相容原理和能量最低原理的内容，晶体中的电子将会依次填充能带。如果电子恰好填满某个能带，并且该能带与最低未占据能带之间存在有限宽度的能隙，则我们将这种晶体称为绝缘体；倘若电子只是部分占据，仍有能带未填满，则我们称之为金属。 金属可以细分为一般金属和拓扑金属。其中，拓扑金属的能带结构包含了一些奇点，即两支能带的交叉点，我们称之为 Weyl node。当Weyl node 恰好落在费米面上时，就会产生一类非常特殊的电子结构：“拓扑半金属”（即 Weyl 半金属）。其中， 砷化钽（TaAs）、磷化钽（TaP）、砷化铌（NbAs）和磷化铌（NbP）等同结构家族材料是天然存在的、非磁性非中心对称的 Weyl 半金属。
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