基于先进计算方法的新奇材料高压研究

Computationally we use pressure to investigate the physical and chemical properties of new and existing energy materials, and to understand the origins of material phenomena. Basic research on materials at the extremes of pressure deepens our understanding of materials behaviors. This enables the elucidation of the fundamentals of chemical interaction at the atomic and electronic levels, and provides access to novel functional materials not otherwise accessible. In many cases, this insight can be applied at ambient conditions as well as extremes to guide new synthetic efforts..Crystal structure prediction using quantum mechanical description has grown rapidly in recent years and now it can be used to uncover structures of solids, point defects, surfaces, and clusters. It has become very powerful to search the most stable structure of a large assembly of atoms by minimizing a common order parameter, enthalpy. In general, we can define any order parameter to be searched for all the possible atomic configurations. In this project, first we propose to predict novel materials, especially focused on hydrides and carbonaceous compounds under pressure. Second, we will optimize our defined order parameters such as entropy, superconductivity, topological insulator, as well as enthalpy. This search strategy can predict novel functional materials such as unprecedented hydrogen-dense hydrides, new form of silicon (photovoltaic applications), low dimensional carbon materials (beyond graphene), new topological insulators, and transparent amorphous oxides.

高压下的凝聚态物理基础研究极大地加深了人们对于材料性质的理解，使得在原子甚至电子层面阐释化学反应机理和发现某些独特的新型功能材料成为可能。在许多情况下，相关结果也可以用于指导常压材料制备与合成。.基于量子力学的晶体结构预测手段在近年来得到了长足的发展，已经可以用来揭示固体、点缺陷、表面和团簇的结构。该方法通过优化序参量焓，在寻找大量原子所能构成的最稳定结构方面展现出了巨大的优势。一般而言，人们也可以定义其他序参量并计算所有可能的原子排布。.本项目采用理论计算手段研究部分材料在高压下的物理化学性质及其深层次机理，主要包括采用理论计算手段预言以高压下氢化物和碳族化合物为主的新奇材料体系，并通过优化各种序参量进行深入研究。希望通过上述研究，预言包括全新氢密材料、在光电池方面有应用前景的新型硅体系、超越石墨烯的低维碳体系、新拓扑绝缘体材料、透明非晶氧化物等新型功能材料。

高温高压下新物态和新材料的探索研究是物理学和材料科学研究的前沿领域，本项目通过第一性原理结构搜索、电子结构、平均场理论、第一性原理分子动力学模拟等手段，对高温高压下新物质形态和新材料及其性质进行了系统研究。主要研究成果如下：1. 拓展了AIRSS程序的三元搜索功能，对Fe-H-O和Fe-Ge-Te体系进行了三元结构搜索，预测了FeO2H和Fe4GeTe2等新型结构，后与实验研究组合作制备了上述新型材料；2. 研究了地球内部的超离子态物质，发现了下地幔含水矿物相的超离子态转变和地球内核铁-轻元素合金的超离子态转变；3. 研究了一系列碳基和硅基高压下的化合物，包括其超导特性、热导特性、离子输运性质等，促进了能源材料在高压下的探索。相关研究获得国内外学者的肯定，发表Nature、Nature Geoscience、Science Advances等文章16篇。