Lanthanum hydride (${\mathrm{LaH}}_{10}$) with a sodalitelike clathrate structure was experimentally synthesized to exhibit a near-room-temperature superconductivity under megabar pressures. Based on first-principles density-functional theory calculations, we reveal that the metal framework of La atoms has excess electrons at interstitial regions. Such anionic electrons are easily captured to form a stable clathrate structure of H cages. We thus propose that the charge transfer from La to H atoms is mostly driven by the electride property of the La framework. Furthermore, the interaction between La atom and H cage induces a delocalization of La $5p$ semicore states to hybridize with the H $1s$ state. Consequently, the bonding nature of ${\mathrm{LaH}}_{10}$ is characterized as a mixture of ionic and covalent bonding between La atom and H cage. Our findings demonstrate that anionic and semicore electrons play important roles in stabilizing clathrate H cages in ${\mathrm{LaH}}_{10}$, which can be broadly applicable to other compressed rare-earth hydrides with clathrate structures.

中文翻译：

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笼形H笼在近室温超导体LaH10中的稳定性和键合性质

氢化镧（$H_{10}$通过实验合成了具有方钠石状包合物的结构，在兆巴压力下表现出近室温的超导性。基于第一性原理的密度泛函理论计算，我们揭示了La原子的金属骨架在间隙区域有多余的电子。此类阴离子电子易于捕获以形成H笼的稳定笼形结构。因此，我们提出从La原子转移到H原子的电荷主要受La骨架的电子性质驱动。此外，La原子与H笼之间的相互作用导致La的离域$5p$ 半核心国家与H杂交 $\mathrm{1个}s$状态。因此，$H_{10}$表征为La原子和H笼之间的离子键和共价键的混合物。我们的研究结果表明，阴离子和半芯电子在稳定笼形H笼中起重要作用。$H_{10}$，可广泛应用于具有包合物结构的其他压缩稀土氢化物。