论文标题
在高压下，电荷转移的基本机制
Underlying mechanism of charge transfer in Li-doped MgH$_{16}$ at high pressure
论文作者
论文摘要
最近报道了锂含锂的氢化镁李$ _2 $ mgh $ _ {16} $ [y。 Sun $ et $ $ al $。，物理。莱特牧师。 {\ bf 123}，097001（2019）]在高压下展示有史以来最高预测的超导过渡温度$ t _ {\ rm c} $。基于第一原理密度功能理论的计算，我们揭示了位于焦基晶格位点的LI掺杂剂会产生分布在间隙区域中的过量电子。这种松散结合的阴离子电子很容易被捕获，以稳定由H笼组成的杂质结构。在h笼中增加了阴离子电子，增强了在费米级别的H衍生的状态电子密度，从而导致高$ t _ {\ rm c} $超导性。因此，我们建议Li掺杂剂的电气性质是Li掺杂剂和H原子之间的电荷转移中的重要成分。我们的发现提供了对高压下的李$ _2 $ _2 $ MGH $ _ {16} $的基本电荷转移机制的更深入的了解。
A lithium-doped magnesium hydride Li$_2$MgH$_{16}$ was recently reported [Y. Sun $et$ $al$., Phys. Rev. Lett. {\bf 123}, 097001 (2019)] to exhibit the highest ever predicted superconducting transition temperature $T_{\rm c}$ under high pressure. Based on first-principles density-functional theory calculations, we reveal that the Li dopants locating in the pyroclore lattice sites give rise to the excess electrons distributed in interstitial regions. Such loosely bound anionic electrons are easily captured to stabilize a clathrate structure consisting of H cages. This addition of anionic electrons to H cages enhances the H-derived electronic density of states at the Fermi level, thereby leading to a high-$T_{\rm c}$ superconductivity. We thus propose that the electride nature of Li dopants is an essential ingredient in the charge transfer between Li dopants and H atoms. Our findings offer a deeper understanding of the underlying mechanism of charge transfer in Li$_2$MgH$_{16}$ at high pressure.
