Structural evolution, electronic and spectral properties of bimetallic Rb2Mgn clusters based on DFT

Abstract

Bimetallic clusters have garnered heightened attention due to their capacity to adjust their intrinsic properties by modifying size, structure, and doping. In this study, we perform a structural search to identify the global minimum of the Rb₂Mg_n (n = 1–12) clusters using the CALYPSO code for structural predicting, followed by DFT optimization. The geometric, electronic and spectral behaviors that vary with size are discussed in depth. Our findings indicate a transition in structure from planar to 3D frameworks at n = 3, then to hollow cage-like structure at n = 8 for Rb₂Mg_n clusters, which happens slightly later than pure magnesium clusters. The convex site is where the Rb atom likes to localize in their structures. Charge transfer studies reveal the electron-loss behavior of Rb along with the presence of sp hybridization in the clusters. Analysis of stability suggests that the Rb₂Mg₃ and Rb₂Mg₉ clusters exhibit greater stability, which is attributed to their closed-shell electronic configurations such as 1S²1P⁶ and 1S²1P⁶1D¹⁰2S². A study of the bonding characteristic not only reveals the delocalization of the bond, but also indicates the stronger Rb–Mg bond than the Mg–Mg bond in Rb₂Mg₃ and Rb₂Mg₉. The spectral characteristics, as determined from IR and Raman spectroscopy, have also been examined.