Probing the structural evolution, electronic and vibrational properties of magnesium clusters doped with sodium atom*

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.