Abstract :
[en] We present a computational study of the M3QX7 family of two-dimensional compounds, focusing specifically on their flat-band properties. We use a high-throughput search methodology, accelerated by machine learning, to explore the vast chemical space spawned by this family. In this way, we identify numerous stable 2D compounds within the M3QX7 family. We investigate how the chemical composition can be manipulated to modulate the position and dispersion of the flat bands. By employing a tight-binding model we explain the formation of flat bands as a result of a relatively loose connection between triangular M3QX3 clusters via bridges of X atoms. The model provides an understanding of the residual interactions that can impact the band dispersion. The same loose connection between clusters not only leads to strongly localized electronic states and thus flat electronic bands but also leads to localized phonon modes and flat bands in the phonon dispersion.
Funding text :
This work used Bridges2 and Expanse at the Pittsburgh Supercomputer (Bridges2) and the San Diego Supercomputer Center (Expanse) through allocation DMR140031 from the Advanced Cyberinfrastructure Coordination Ecosystem: Services & Support (ACCESS) program, which National Science Foundation supports grants 2138259, 2138286, 2138307, 2137603, and 2138296. AHR and LW were funded, in part, by the Luxembourg National Research Fund (FNR), Inter Mobility 2DOPMA, grant reference 15627293. AHR also recognizes the support of the WV-HEPC RCG Award 2023 and NASA EPSCoR Award 80NSSC22M0173. MALM acknowledges the computing time on the high-performance computer Noctua 2 at the NHR Center PC through the project hpc-prf-ecsm and hpc-prf-vibff and the Gauss Centre for Supercomputing e.V. ( www.gauss-centre.eu ) for providing computing time on the GCS Supercomputer SUPERMUC-NG at Leibniz Supercomputing Centre ( https://www.lrz.de ) under the project pn25co.
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