Probing the structural evolution, electronic and spectral properties of bimetallic K2Mgn clusters: A DFT study

Abstract

We report a systemic exploration to determine the global minimum geometries of the K₂Mg_n (n = 1–12) clusters. This is accomplished by utilizing the CALYPSO code for geometric prediction, subsequently refined through DFT-based optimization. The results reveal a structural transition from planar to three-dimensional framework at n = 3, followed by the formation of a hollow cage-like structure at n = 8. This transition occurs slightly later compared to pure Mg clusters. The convex site is identified as the preferred localization point for K atoms within these structures. Additionally, there is a charge transfer from K to Mg, providing evidence for sp hybridization within the clusters. The stability study shows the outstanding stability of K₂Mg₃ and K₂Mg₉, which can be attributed to the closed-shell configurations of 1S²1P⁶ and 1S²1P⁶1D¹⁰2S². Analysis of bonding characteristics highlights the delocalization of bonds in K₂Mg₃ and K₂Mg₉, in which there is much weaker K-Mg interaction than the Mg-Mg interaction. Finally, a comprehensive evaluation of the spectral properties, as characterized by IR and Raman spectroscopy, has been investigated.