SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 12: Poster Session I: Electronic structure theory: General
O 12.1: Poster
Montag, 1. März 2021, 10:30–12:30, P
Electronic Structure of Cesium-based Photocathode Materials from Density Functional Theory — •Holger-Dietrich Saßnick1 and Caterina Cocchi1,2 — 1Institut für Physik - Carl von Ossietzky Universität Oldenburg, 26129 Oldenburg, Germany — 2Institut für Physik - Humboldt-Universität zu Berlin und IRIS Adlershof, 12489 Berlin, Germany
The development of novel materials for vacuum electron sources is an active field of research that can greatly benefit from the results of ab initio calculations [1]. Density functional theory offers a good compromise between accuracy and computational feasibility, however, its results crucially depend on the choice of the exchange-correlation potential, vxc. To address this point, we systematically analyze the performance of three popular approximations of vxc (PBE, SCAN and HSE06) on the structural and electronic properties of bulk Cs3Sb and Cs2Te, two representative Cs-based semiconductors employed in photocathode applications. We find that PBE shows expectedly the largest discrepancies from the target, while both SCAN and HSE06 perform remarkably well in reproducing the materials properties. Additionally, we study the effect of spin-orbit coupling which mainly impacts the valence region of both materials inducing a band splitting of about 150 meV. Our results indicate SCAN as the best trade-off between accuracy and computational costs, outperforming the considerably more expensive HSE06 [2].
[1] Cocchi et al, J. Phys.: Condens. Matter 2019, 31, 014002
[2] Saßnick & Cocchi, submitted 2020, arXiv:2101.04596