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

Abstract

Geometries, stabilities, bonding nature, and vibrational properties of bimetallic KMg_n^0/– (n = 2–12) clusters have been comprehensively studied by CALYPSO code within DFT calculations. The results reveal the structural transition from 2D to 3D at n = 3. From n ≥ 8, the geometry of KMg_n^0/– transfers a hollow framework with a six-atom triangular prism unit. By comparing the geometry of neutral and anionic KMg_n^0/– clusters, most of them are structurally different. In all doped clusters, the K atoms tend to localize on the convex positions of the skeleton and play the role of electron donors. Two highly stable clusters KMg₉ and KMg₉^– have been found, and studies showed that the prominent stability benefits from their compact magnesium structural motifs and quasi-full/full shell electronic configurations. Additionally, bonding nature analysis reflects there is much weak K-Mg interaction than Mg-Mg interaction in the KMg₉^0/– clusters. The spectroscopic properties based on the PES, IR and Raman spectra have also been discussed.