Probing the structural evolution, electronic and vibrational properties of anionic sodium-doped magnesium clusters

Abstract

Bimetallic clusters aroused a great deal of attention in materials science because of their novel properties, depending sensitively on their size, structure, and composition. Herein, we report a theoretical study of the geometry, stability, electronic and vibrational properties of bimetallic NaMgn– (n = 2–11) clusters through CALYPSO code within DFT calculations. The most stable NaMgn– clusters were found to be planar structure at n = 2, triangular pyramid-based structure at n = 3–5, pentagonal pyramid-based structure at n = 6–7 and the triangular prism-based structure at n = 8–11. Most of them are structurally consistent with anionic magnesium clusters, in which the Na atom tends to localize on the convex site. Stability studies conform to the NaMg3– and NaMg9–clusters to being the magic number structure with prominent stability, which benefits from short interatomic bonds and closed-shell 1S21P6 and 1S21P61D102S2 electronic configurations. Bonding nature analysis not only reflects the delocalized bonding properties in the NaMg3– and NaMg9– clusters, but also reveals that the Mg-Mg bond is stronger than the Na-Mg bond. For the NaMgn– clusters, calculated PES, IR, and Raman spectra could be used as essential evidence for identifying cluster structures experimentally in the future.