二维层状的过渡金属二硫族化合物呈现出丰富的物理性质，其中许多材料具有电荷密度波和超导电性。该类化合物的性质对材料的化学组分、掺杂以及外压力等比较敏感。毫无疑问，宏观性质的变化是与材料的微观结构密切关联的。从实验和理论上弄清楚这种关联性对解释电荷密度波和超导的微观物理起源具有重要意义。本项目拟通过化学气相输运方法生长一类典型的TaX2 (X=S, Se)母体及其各种掺杂的单晶材料，利用X射线吸收光谱技术研究材料的局域原子结构与电子结构；通过与宏观电输运性质进行比较，探讨掺杂、缺陷、原子有序度等对电荷密度波和超导电性的调控规律性。我们将结合第一性原理与电子多重散射理论对X射线吸收谱进行解释，深入理解局域原子结构和电子结构与宏观性质的内在关联。本项目的研究能够为进一步揭示出过渡金属二硫族化合物的电荷密度波与超导电性的物理起源提供基础，同时也能为实验上有效调控此类材料提供一定的参考。

Layered transition metal dichalcogenides (TMD) have rich physical properties. Some of them usually have charge density wave (CDW) and superconductivity. The above properties are sensitive to the chemical elements, doping, and external pressure. Undoubtedly, the macroscopical properties are related to the micro-structure. So it’s important to study the relationship between them in experiments and theory. In this project, we plan to grow the typical TaX2 (X=S, Se) single crystals by chemical vapor transport. We will study the local atom and electron structures by using X-ray absorption spectrum (XAS) technique. By comparing the transport property we investigate the effects of the doping, defect, and atomic order on the charge density wave and superconductivity. We also explain the experimental X-ray absorption spectrum based on the first-principle theory and multi-scattering theory, in order to deeply understand the relationship between the local atom structure and the macroscopical transport property. Our study can give further understanding of the physical origins of CDW and superconductivity and also help to tune the TMD materials effectively in experiments.