Deuterium spectroscopy for enhanced bounds on physics beyond the standard model

We consider the impact of combining precision spectroscopic measurements made in atomic hydrogen with similar measurements made in atomic deuterium on the search for physics beyond the Standard Model. Specifically we consider the wide class of models that can be described by an effective Yukawa-type interaction between the nucleus and the electron. We find that it is possible to set bounds on new light-mass bosons that are orders of magnitude more sensitive than those set using a single isotope only, provided the interaction couples differently to the deuteron and proton. Further enhancements of these bounds by an order of magnitude or more would be made possible by extending the current measurements of the isotope shift of the 1s$_{1/2}$-2s$_{1/2}$ transition frequency to that of a transition between the 2s$_{1/2}$ state and a Rydberg s-state.Comment: 16 pages, 9 figure

Deuterium spectroscopy for enhanced bounds on physics beyond the Standard Model

We consider the impact of combining precision spectroscopic measurements made in atomic hydrogen with similar measurements made in atomic deuterium on the search for physics beyond the Standard Model. Specifically we consider the wide class of models that can be described by an effective Yukawa-type interaction between the nucleus and the electron. We find that it is possible to set bounds on new light-mass bosons that are orders of magnitude more sensitive than those set using a single isotope only, provided the interaction couples differently to the deuteron and proton. Further enhancements of these bounds by an order of magnitude or more would be made possible by extending the current measurements of the isotope shift of the 1s$_{1/2}$-2s$_{1/2}$ transition frequency to that of a transition between the 2s$_{1/2}$ state and a Rydberg s-state.Comment: 16 pages, 9 figure

Cu₂SiSe₃ as a promising solar absorber: harnessing cation dissimilarity to avoid killer antisites

Copper-chalcogenides are promising candidates for thin film photovoltaics due to their ideal electronic structure and potential for defect tolerance. To this end, we have theoretically investigated the optoelectronic properties of Cu₂SiSe₃, due to its simple ternary composition, and the favourable difference in charge and size between the cation species, limiting antisite defects and cation disorder. We find it to have an ideal, direct bandgap of 1.52 eV and a maximum efficiency of 30% for a 1.5 μm-thick film at the radiative limit. Using hybrid density functional theory, the formation energies of all intrinsic defects are calculated, revealing the p-type copper vacancy as the dominant defect species, which forms a perturbed host state. Overall, defect concentrations are predicted to be low and have limited impact on non-radiative recombination, as a consequence of the p–d coupling and antibonding character at the valence band maxima. Therefore, we propose that Cu₂SiSe₃ should be investigated further as a potential defect-tolerant photovoltaic absorber

Interplay of Static and Dynamic Disorder in the Mixed-Metal Chalcohalide Sn₂SbS₂I₃

Chalcohalide mixed anion crystals have seen a rise in interest as perovskite inspired materials with the goal of combining the ambient stability of metal chalcogenides with the exceptional optoelectronic performance of metal halides. Sn2SbS2I3 is a promising candidate, having achieved a photovoltaic power conversion efficiency above 4 . However, there is uncertainty over the crystal structure and physical properties of this crystal family. Using a first principles cluster expansion approach, we predict a disordered room temperature structure, comprising both static and dynamic cation disorder on different crystallographic sites. These predictions are confirmed using single crystal X ray diffraction. Disorder leads to a lowering of the bandgap from 1.8 eV at low temperature to 1.5 eV at the experimental annealing temperature of 573 K. Cation disorder tailoring the bandgap allows for targeted application or for the use in a graded solar cell, which when combined with material properties associated with defect and disorder tolerance, encourages further investigation into the group IV V chalcohalide family for optoelectronic application

Interplay of Static and Dynamic Disorder in the Mixed-Metal Chalcohalide Sn2SbS2I3

Chalcohalide mixed-anion crystals have seen a rise in interest as "perovskite-inspired materials" with the goal of combining the ambient stability of metal chalcogenides with the exceptional optoelectronic performance of metal halides. Sn2SbS2I3 is a promising candidate, having achieved a photovoltaic power conversion efficiency above 4%. However, there is uncertainty over the crystal structure and physical properties of this crystal family. Using a first-principles cluster expansion approach, we predict a disordered room-temperature structure, comprising both static and dynamic cation disorder on different crystallographic sites. These predictions are confirmed using single-crystal X-ray diffraction. Disorder leads to a lowering of the bandgap from 1.8 eV at low temperature to 1.5 eV at the experimental annealing temperature of 573 K. Cation disorder tailoring the bandgap allows for targeted application or for the use in a graded solar cell, which when combined with material properties associated with defect and disorder tolerance, encourages further investigation into the group IV/V chalcohalide family for optoelectronic applications

Interplay of Static and Dynamic Disorder in the Mixed-Metal Chalcohalide Sn2SbS2I3

Chalcohalide mixed-anion crystals have seen a rise in interest as “perovskite-inspired materials” with the goal of combining the ambient stability of metal chalcogenides with the exceptional optoelectronic performance of metal halides. Sn2SbS2I3 is a promising candidate, having achieved a photovoltaic power conversion efficiency above 4%. However, there is uncertainty over the crystal structure and physical properties of this crystal family. Using a first-principles cluster expansion approach, we predict a disordered room-temperature structure, comprising both static and dynamic cation disorder on different crystallographic sites. These predictions are confirmed using single-crystal X-ray diffraction. Disorder leads to a lowering of the bandgap from 1.8 eV at low temperature to 1.5 eV at the experimental annealing temperature of 573 K. Cation disorder tailoring the bandgap allows for targeted application or for the use in a graded solar cell, which when combined with material properties associated with defect and disorder tolerance, encourages further investigation into the group IV/V chalcohalide family for optoelectronic applications

SMTG-UCL/easyunfold: v0.3.1

What's Changed Fix a bug when parsing PROCAR with spin polarsation by @zhubonan in https://github.com/SMTG-UCL/easyunfold/pull/32 Full Changelog: https://github.com/SMTG-UCL/easyunfold/compare/v0.3.0...v0.3.

SMTG-Bham/easyunfold: v0.3.2

<h2>What's Changed</h2> <ul> <li>Update README.md by @alexsquires in https://github.com/SMTG-Bham/easyunfold/pull/33</li> <li>Update commensurability warning by @kavanase in https://github.com/SMTG-Bham/easyunfold/pull/37</li> <li>Fix wrapping kpoints at -0.5/0.5 by @zhubonan in https://github.com/SMTG-Bham/easyunfold/pull/39</li> <li>Bug fix handling multiple spins in projected plots by @kavanase in https://github.com/SMTG-Bham/easyunfold/issues/31</li> <li>General docs & tests updates by @kavanase</li> </ul> <h2>New Contributors</h2> <ul> <li>@alexsquires made their first contribution in https://github.com/SMTG-Bham/easyunfold/pull/33</li> </ul> <p><strong>Full Changelog</strong>: https://github.com/SMTG-Bham/easyunfold/compare/v0.3.1...v0.3.2</p&gt