论文标题
从混合DFT计算中洞悉固体溴的高压行为
Insights into the high-pressure behaviour of solid bromine from hybrid DFT calculations
论文作者
论文摘要
了解高压下分子固体的特性是新固态理论发展的关键要素。但是，密度功能理论（DFT）的最常用的广义梯度近似（GGA）通常无法正确描述这些系统在高压下的行为。在这里，我们利用混合DFT方法在高压下对元素溴的性质进行建模。该计算与实验非常一致地繁殖了分子I期（CMCA对称性）的性质及其压力诱导的过渡到非分子II期（IMMM）。预计在128 GPA的实验但未观察到的转变为III期（I4/MMM），然后在188 GPA处形成FCC晶格。对建模相的结构和电子特性的分析表明，分子CMCA相在其稳定性的边界上变成金属，IMMM和I4/MMM相都是金属和准2D。最后，我们表明，从实验中假设的溴的不一致阶段是瞬态物种，可以将其视为中间体，在从I期到II期的过渡的边界处发生的离解过程中。
Understanding the properties of molecular solids at high pressure is a key element in the development of new solid-state theories. However, the most commonly used generalized-gradient approximation (GGA) of the density functional theory (DFT) often fails to correctly describe the behavior of these systems at high pressure. Here we utilize the hybrid DFT approach to model the properties of elemental bromine at high pressure. The calculations reproduce in very good agreement with experiment the properties of the molecular phase I (Cmca symmetry) and its pressure-induced transition into the non-molecular phase II (Immm). The experimentally yet unobserved transition into phase III (I4/mmm) is predicted to occur at 128 GPa, followed by subsequent formation of an fcc lattice at 188 GPa. Analysis of the structure and electronic properties of the modelled phases indicates that the molecular Cmca phase becomes metallic just at the borderline of its stability, and that both Immm and I4/mmm phases are metallic and quasi-2D. Finally, we show that the incommensurate phases of bromine postulated from experiment are transient species which can be viewed as intermediates in the dissociation process occurring at the boundary of the transition from phase I to phase II.
