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Bimetallic sodium-doped magnesium cluster cations, NaMgn+(n= 2–12), have been investigated through a synergetic combination of the CALYPSO code and DFT calculations. The results reveal that the lowest-energy structures of NaMgn+ exhibit linear, planar, triangular pyramid, pentagonal pyramid, and triangular prism topologies. The structures can be described as a substituted geometry of pure Mg clusters at the small size. Starting from n = 9, the dominant structures transform into a triangular prism-based configuration. Like anionic and neutral NaMgn clusters, the Na atom prefers the peripheral regions of the Mgn framework. Stability studies indicate NaMg4+ and NaMg10+ to be the~most stable clusters, which may benefit from their closed-shell electron structures. Analysis of the bonding nature shows stronger Mg-Mg interaction than the Na-Mg interaction in the NaMg4+ and NaMg10+ clusters. The reason is that covalent bonds are formed in the Mg-Mg regions, while there is no aggregation of electron density in the Na-Mg regions. [ABSTRACT FROM AUTHOR]

The structures, stabilities, bonding characters, electronic and vibrational properties of bimetallic NaMgn (n = 2–11) clusters have been comprehensively studied by CALYPSO code within DFT calculations. The results show that the geometries of the most stable NaMgn clusters evolve from 2D to 3D framework at n = 3, and appear the triangular prism-based structural unit at n = 8. Most can be viewed as a substituted structure of the corresponding magnesium clusters. The Na atom occupies the convex site of the NaMgn motifs. Positive charges of all Na atoms signify the charge transfers from Na to Mg in said clusters. Stability studies suggest the outstanding stability of the NaMg9 cluster in the size range of n = 2–11. Analysis of bonding nature reveals mixed covalent and metallic Na-Mg and Mg-Mg bonds with delocalized nature in NaMg9, in which the bond strength of the Na-Mg bond is lower than that of the Mg-Mg bond. The simulated IR and Raman spectra could provide additional ways to identify the structure of the NaMgn clusters in the following experiments. [ABSTRACT FROM AUTHOR]