超导H3S中电子-声子顶点修正效应
Electron-phonon vertex correction effect in superconducting H3S
AI总结：
研究H3S中电子-声子顶点修正对超导性质的影响，发现其显著提升临界温度预测精度，而对Pb影响较小。
AI中文摘要：
Migdal-Eliashberg（ME）形式化为描述声子介导超导性提供了可靠的框架，在亚达莫夫极限下，即电子费米能超过特征声子能时。在本工作中，我们超越这一限制，通过在Eliashberg形式化中引入一阶顶点修正到电子-声子（e-ph）相互作用，并评估其对H3S和Pb超导性质的影响。对于H3S，其中亚达莫夫假设失效，我们发现顶点修正对e-ph耦合影响显著。当结合声子非谐性和电子态密度的能量依赖性时，预测的临界温度（Tc）与实验观测非常吻合。相比之下，对于元素Pb，其中亚达莫夫近似仍然有效，顶点修正影响微小，计算出的Tc和超导能隙与标准ME形式化的预测非常接近。这些发现表明，在强耦合高临界温度氢化物中非亚达莫夫修正的重要性，并建立了一个稳健的原理计算框架，以准确预测不同区域的超导性质。
英文摘要：
The Migdal-Eliashberg (ME) formalism provides a reliable framework for describing phonon-mediated superconductivity in the adiabatic regime, where the electronic Fermi energy exceeds the characteristic phonon energy. In this work, we go beyond this limit by incorporating first-order vertex corrections to the electron-phonon (e-ph) interaction within the Eliashberg formalism and assess their impact on the superconducting properties of H3S and Pb using first-principles calculations. For H3S, where the adiabatic assumption breaks down, we find that vertex corrections to the e-ph coupling are substantial. When combined with phonon anharmonicity and the energy dependence of the electronic density of states, the predicted critical temperature (Tc) is in very good agreement with experimental observations. In contrast, for elemental Pb, where the adiabatic approximation remains valid, vertex corrections have a negligible effect, and the calculated Tc and superconducting gap closely match the predictions of the standard ME formalism. These findings demonstrate the importance of non-adiabatic corrections in strongly coupled high-Tc hydrides and establish a robust first-principles framework for accurately predicting superconducting properties across different regimes.
