非谐性与库仑赝势效应对 YH$_6$ 和 YH$_9$ 超导电性的影响
Anharmonicity and Coulomb pseudopotential effects on superconductivity in YH$_6$ and YH$_9$
AI总结：
本文用随机路径积分方法研究钇氢化物的非谐效应，发现正确考虑库仑赝势的频率截断重整化后，非谐效应足以解释 YH$_6$ 和 YH$_9$ 超导转变温度的理论与实验偏差。
AI中文摘要：
非谐效应被广泛认为是理论预测中高估钇氢化物 YH$_6$ 和 YH$_9$ 超导转变温度的主要原因。然而，先前的研究表明，仅靠非谐性可能不足以解释这一偏差。在本工作中，我们采用随机路径积分方法研究钇氢化物中离子的量子效应和非谐效应。我们的计算揭示了相对于密度泛函微扰理论，电子-声子耦合参数存在显著修正，且平均声子频率有所提高，这与随机自洽简谐近似的结果高度一致。我们发现，正确考虑由于频率截断而导致的库仑赝势重整化（在以往计算中常被忽略）对于预测与 YH$_6$ 和 YH$_9$ 实验值一致的转变温度至关重要。这表明，在加入这一修正后，非谐效应足以解释实验与理论结果之间的偏差。
英文摘要：
Anharmonic effects are widely believed to be the primary cause of the overestimation of superconducting transition temperatures of yttrium hydrides YH$_6$ and YH$_9$ in theoretical predictions. However, prior studies indicate that anharmonicity alone may be insufficient to account for this discrepancy. In this work, we employ the stochastic path-integral approach to investigate the quantum and anharmonic effects of ions in yttrium hydrides. Our calculations reveal significant corrections to the electron-phonon coupling parameters and an increase in the average phonon frequency compared to density functional perturbation theory, aligning closely with results from the stochastic self-consistent harmonic approximation. We find that properly taking into account the renormalization of the Coulomb pseudopotential due to the frequency cutoff, which is often overlooked in previous calculations, is critical to predicting transition temperatures consistent with experimental values for both YH$_6$ and YH$_9$. This indicates that, with this correction, anharmonic effects are sufficient to explain the discrepancies between experimental and theoretical results.
