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Abstract We study the magneto-optical properties of Fe–Co–Al ordered alloys in the terahertz range of frequencies. Using the standard Kubo-based approach to compute intrinsic part of the ${\sigma }_{xy}\left(\omega \right)$we find a strong dependence ofσ_xyonωin the terahertz range. For example, we find that below 10 THz Co₃Al has nearly constantσ_xyand that above 10 THz it is reduced by about 50 times. Furthermore, we find a strong dependence ofσ_xyon the chemical composition. For example, we find that the addition of Al to Fe changes the sign ofσ_xy, while the addition of Co to Fe leads to a nonmonotonic dependence ofσ_xyon Co concentration. 

Abstract Abundant transition metal borides are emerging as substitute electrochemical hydrogen evolution reaction (HER) catalysts for noble metals. Herein, an unusual canonic‐like behavior of theclattice parameter in the AlB₂‐type solid solution Cr_1–xMo_xB₂(x= 0, 0.25, 0.4, 0.5, 0.6, 0.75, 1) and its direct correlation to the HER activity in 0.5 M H₂SO₄solution are reported. The activity increases with increasingx, reaching its maximum atx= 0.6 before decreasing again. At high current densities, Cr_0.4Mo_0.6B₂outperforms Pt/C, as it needs 180 mV less overpotential to drive an 800 mA cm⁻²current density. Cr_0.4Mo_0.6B₂has excellent long‐term stability and durability showing no significant activity loss after 5000 cycles and 25 h of operation in acid. First‐principles calculations have correctly reproduced the nonlinear dependence of theclattice parameter and have shown that the mixed metal/B layers, such as (110), promote hydrogen evolution more efficiently forx= 0.6, supporting the experimental results. 

WfBase is a software package providing an easy way to compute from first-principles various properties depending on the electronic structure of periodic solids. This package can parse user-provided mathematical expressions, in a human-readable format, using the Einstein notation for indices. This package also comes with a built-in database of some simple materials. For more details, please see:  https://coh.ucr.edu/wfbase