Ising superconductivity, observed in NbSe₂ and similar materials, has generated tremendous interest. Recently, attention was called to the possible role that spin fluctuations (SF) play in this phenomenon, in addition to the dominant electron–phonon coupling (EPC); the possibility of a predominantly triplet state was discussed and led to a conjecture of viable singlet–triplet Leggett oscillations. However, these hypotheses have not been put to a quantitative test. In this paper, we report first principle calculations of the EPC and also estimate coupling with SF, including full momentum dependence. We find that: (1) EPC is strongly anisotropic, largely coming from the \(K-{K}^{{\prime} }\) scattering, and therefore excludes triplet symmetry even as an excited state; (2) superconductivity is substantially weakened by SF, but anisotropy remains as above; and, (3) we do find the possibility of a Leggett mode, not in a singlet–triplet but in an s₊₊ – s_± channel.

_{在 NbSe 2}和类似材料中观察到的伊辛超导性引起了极大的兴趣。最近，除了主要的电子-声子耦合 (EPC) 之外，人们还注意到自旋涨落 (SF) 在这种现象中可能发挥的作用；讨论了以三重态为主的可能性，并得出了可行的单重态-三重态 Leggett 振荡的猜想。然而，这些假设尚未经过定量检验。在本文中，我们报告了 EPC 的第一性原理计算，还估计了与 SF 的耦合，包括完全动量依赖性。我们发现：(1) EPC 具有很强的各向异性，主要来自\(K-{K}^{{\prime} }\)散射，因此即使作为激发态也排除三重态对称性；(2)超导性被SF大幅削弱，但各向异性仍如上；并且，(3) 我们确实发现了 Leggett 模式的可能性，不是在单重态-三重态中，而是在s ₊₊ – s _±通道中。