论文标题
从头算研究钯氢化物中四面体位点的占领及其对超导性的影响
Ab initio study of metastable occupation of tetrahedral sites in palladium hydrides and its impact on superconductivity
论文作者
论文摘要
最近对钯氢化物的实验研究表明，占据四面体位点的氢原子的亚稳态结构可能导致超过50 K以上的超导性，与稳定结构的10 K临界温度相比，所有氢原子均占据了八面体位点。通过用氢原子生成许多结构，可以随机占据以面部为中心的立方晶格的八面体和四面体位点，并在与第一原理的不同理论水平下计算其能量，我们确定即使在四面体位点的部分或完全占用了四面体位点，即使是量化量子量的量子量子和量子量的量子量，也可能包括量度量子量的量子。当氢原子占据八面体位点时，非谐性在钯氢化物中至关重要，并且实际上使具有全八面体占领的结构成为基态。尽管存在具有完全或部分四面体位点职业的结构，但随着四面体位点的数量，超导临界温度却降低。我们的计算丢弃了四面体部位的占用可以增加钯氢化钯的临界温度。
A recent experimental work on palladium hydrides suggested that metastable structures with hydrogen atoms occupying tetrahedral sites could lead to superconductivity above 50 K, a huge increase compared to the 10 K critical temperature of the stable structure with all hydrogen atoms occupying octahedral sites. By generating many structures with hydrogen atoms randomly occupying the octahedral and tetrahedral sites of the face-centered cubic lattice and calculating their energy at different theoretical levels from first principles, we determine that metastable structures with partial or full occupation of tetrahedral sites are possible, even when the ionic quantum zero-point energy and anharmonicity are included in the calculations. Anharmonicity is crucial in palladium hydrides when hydrogen atoms occupy octahedral sites and, in fact, makes the structure with full octahedral occupation the ground state. Despite the metastable existence of structures with full or partial tetrahedral sites occupation, the superconducting critical temperature is reduced with the number of tetrahedral sites occupied. Our calculations discard that the occupation of tetrahedral sites can increase the critical temperature in palladium hydrides.
