实验和理论均证实高压下惰性元素与小分子可以通过分子间弱相互作用结合成新型分子化合物，这一现象引起高压学界的广泛关注。我们将这类分子化合物称之为惰性元素-小分子化合物。这类化合物广泛存在于地球等行星内部。目前，对这类分子化合物的研究主要集中在高压实验合成上，但关于其结构、相图、相变机制、分子间相互作用、电子行为等方面的研究却鲜有报道。本项目拟采用基于密度泛函理论的第一性原理方法，结合晶体结构搜索技术，选择惰性元素（He、Xe）和典型小分子（H2、N2、O2、CO2、H2O、CH4、NH3等）在高压下形成的新型惰性元素-小分子化合物为研究对象，探索其在高压下的晶体结构，建立高压相图；确定化合物内部分子间多种相互作用的耦合机制；揭示化合物中惰性元素在高压下获得化学活性的物理本质。该项目的实施不仅能加深对惰性元素-小分子化合物的理解，也将为新材料设计和行星科学研究提供理论支撑。

The inert elements and molecules can form novel molecular compounds under high pressure. This has been confirmed by the experimental and theoretical results. This phenomenon attracted much attention in high pressure science. We name them as inert element-molecule compounds. In addition, this kind of molecular compound is also seen as important reference in the planetary science. At present, a number of studies have been devoted to the high-pressure synthesis of these molecular compounds. However, many fundamental aspects of these molecular compounds, such as high-pressure structures, phase diagram, the mechanism of high pressure phase transition and synthesis, intermolecular interactions, electronic behavior etc. are still not well understood. So this kind of molecular compounds synthesized by the inert elements (He, Xe) and typical small molecules (H2, N2, O2, CO2, H2O, CH4, NH3 and so on) under high pressure, will be studied in this project by means of the first principle calculations based on density functional theory and crystal structure search technology. This project aims to explore high-pressure crystal structures of these molecular compounds, construct the high-pressure phase diagram, get the coupling mechanism of multiple interactions, reveal the nature of chemical activity of inert elements under high pressure. This project will not only deepen our understanding of novel inert element-molecule compounds, but also provide important theoretical support for the studies of novel materials and planetary science.