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Abstract Migdal-Eliashberg theory is one of the state-of-the-art methods for describing conventional superconductors from first principles. However, widely used implementations assume a constant density of states around the Fermi level, which hinders a proper description of materials with distinct features in its vicinity. Here, we present an implementation of the Migdal-Eliashberg theory within the EPW code that considers the full electronic structure and accommodates scattering processes beyond the Fermi surface. To significantly reduce computational costs, we introduce a non-uniform sampling scheme along the imaginary axis. We demonstrate the power of our implementation by applying it to the sodalite-like clathrates YH₆and CaH₆, and to the covalently-bonded H₃S and D₃S. Furthermore, we investigate the effect of maximizing the density of states at the Fermi level in doped H₃S and BaSiH₈within the full-bandwidth treatment compared to the constant-density-of-states approximation. Our findings highlight the importance of this advanced treatment in such complex materials. 

Abstract The Zintl compound TlInTe₂is an intriguing material because of its outstanding thermoelectric properties at ambient pressure. Interestingly, it has recently been found that TlInTe₂exhibits a V-shape dependence of the superconducting critical temperature (T_c) under increasing pressure, which has been linked to the reversed behavior of the Raman active A_gphonon mode and anharmonic effects. In this study, we have performed first-principles calculations of the electron-phonon interactions and the superconducting properties of TlInTe₂in order to understand this unusual pressure-induced response. In contrast to experiment, we find a dome-shaped pressure-induced dependence ofT_cwith a maximum value of 0.23 K at 18 GPa, significantly lower than the experimental results. Electron doping has the potential to adjust theT_cto fall within the experimental range, but it necessitates considerably high levels of doping. Furthermore, our analysis of the phonon spectra and phonon lifetimes, including anharmonic effects, show that anharmonicity is unlikely to influence the superconducting properties of TlInTe₂. It remains an open question whether there is indeed an unusual V-shapeT_cdependence with pressure or whether the phonon-mediated theory of superconductivity used here breaks down in this system. 

Abstract Ising superconductivity, observed in NbSe₂and 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$$K-{K}^{{\prime} }$$ $K-K^{\prime }$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 ans₊₊–s_±channel. 

EPW is an open-source software for ab initio calculations of electron–phonon interactions and related materials properties. The code combines density functional perturbation theory and maximally localized Wannier functions to efficiently compute electron–phonon coupling matrix elements, and to perform predictive calculations of temperature-dependent properties and phonon-assisted quantum processes in bulk solids and low-dimensional materials. Here, we report on significant developments in the code since 2016, namely: a transport module for the calculation of charge carrier mobility under electric and magnetic fields using the Boltzmann transport equation; a superconductivity module for calculations of phonon-mediated superconductors using the anisotropic multi-band Eliashberg theory; an optics module for calculations of phonon-assisted indirect transitions; a module for the calculation of small and large polarons without supercells; and a module for calculating band structure renormalization and temperature-dependent optical spectra using the special displacement method. For each capability, we outline the methodology and implementation and provide example calculations. 

Gold is one of the most inert metals, forming very few compounds, and only a few of them are currently known to be superconducting. Here we have found yet another chemical compound of gold (and silver) that is superconducting. 

A new member of the transition metal dichalcogenide (TMD) family, 2M-WS 2, has been recently discovered and shown to display superconductivity with a critical temperature (Tc) of 8.8 K, the highest Tc among superconducting TMDs at ambient pressure. Using first-principles calculations combined with the Migdal-Eliashberg formalism, we explore how the superconducting properties of 2M-WS 2 can be enhanced through doping. Mo, Nb, and Ta are used as dopants at the W sites, while Se is used at the S sites. We demonstrate that the monotonous decrease in the Tc observed experimentally for Mo and Se doping is due to the decrease in density of states at the Fermi level and the electron–phonon coupling of the low-energy phonons. In addition, we find that a noticeable increase in the electron–phonon coupling could be achieved when doping with Nb and Ta, leading to an enhancement of the Tc of up to 50% compared to the undoped compound.