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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. 

Molecular orbital symmetry plays a pivotal role in determining chemical reaction mechanisms. The process of changing chemical reactants into products must transition along a pathway that conserves molecular orbital symmetry to ensure continuity. This principle is so fundamental that reactions that do not conserve symmetry are typically considered “forbidden” due to the high resultant energy barriers. Here, it is demonstrated that it is possible to electrically catalyze these forbidden transitions when a single molecule is bound between two electrodes in a nanoscale junction. A cycloaddition reaction is induced in a norbornadiene (NBD) derivative, converting it to quadricyclane (QC) by utilizing nanoconfinement to place the molecule into a configuration that is far from equilibrium and applying a small voltage to the molecular junction. Traditionally, this reaction can only be induced photochemically due to orbital symmetry selection rules. By directly tracking the reaction dynamics in situ using single‐molecule Raman spectroscopy, it is shown that for this reaction to be electrically catalyzed the molecule must be sterically maneuvered into a configuration near the transition state at the peak of the energy barrier prior to applying the voltage needed to successfully induce the forbidden transition is applied. 

Abstract The Laser Interferometer Space Antenna (LISA) has the potential to reveal wonders about the fundamental theory of nature at play in the extreme gravity regime, where the gravitational interaction is both strong and dynamical. In this white paper, the Fundamental Physics Working Group of the LISA Consortium summarizes the current topics in fundamental physics where LISA observations of gravitational waves can be expected to provide key input. We provide the briefest of reviews to then delineate avenues for future research directions and to discuss connections between this working group, other working groups and the consortium work package teams. These connections must be developed for LISA to live up to its science potential in these areas.