论文标题
高压分子晶体氢的金属和半金属状态
Metallic and semimetallic states of molecular crystalline hydrogen at high pressures
论文作者
论文摘要
在密度函数理论框架内的初始分子动力学方法用于分析在温度100 \，k下晶体分子氢的结构和电子特性。计算压力，配对相关函数和带结构。在压缩范围302-626 \ GPA的压缩范围内，观察到分子晶体从半金属和金属状态的分子晶体氢的交叉。在361 \，GPA以下的压力下，具有C2/C结构的分子晶体是具有间接间隙的半导体。在压力范围361-527 \，GPA中，单斜C2/c晶格的带状结构具有特征性的半学分，并具有部分无占空地的价值带和部分占据的传导带。当压缩到高于544 \的压力时，结构从单斜晶C2/C到正交CMCA的变化，伴随着直接间隙的值急剧下降（超过两个数量级），这是所得结构金属电导率的指示。金属状态是亚稳态的，并存在至626 \ gpa的压力。
Ab initio molecular dynamic method within the framework of density functional theory is applied to analyze the structural and electronic properties of crystalline molecular hydrogen at temperature 100\,K. Pressure, pair correlation function and band structure are calculated. The crossover of molecular crystalline hydrogen from the state of a semiconductor to a semimetallic and metallic state is observed upon compression in the pressure range of 302-626\,GPa. At pressures below 361\,GPa, the molecular crystal with the C2/c structure is a semiconductor with an indirect gap. In the pressure range 361 - 527\,GPa, band structure of the monoclinic C2/c lattice has a characteristic semimetalic profile with partially unoccupied valence band and partially occupied conduction band. When compressed to pressures above 544\,GPa, the structure changes from monoclinic C2/c to orthorhombic Cmca, accompanied by a sharp decrease (by more than two orders of magnitude) in the value of the direct gap, which is an indication of the metallic conductivity of the resulting structure. The metallic state is metastable and exists up to a pressure of 626\,GPa.
