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

•The most stable structures of the KMgn0/– (n = 2–12) clusters are determined.•The evolution of the structure and stability has be elucidated.•Two structures, KMg9 and KMg9–, are uncovered and proved to be the magic number clusters with prominent stability.•The electronic and vibrational properties as well as bonding nature are discussed. Geometries, stabilities, bonding nature, and vibrational properties of bimetallic KMgn0/– (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 KMgn0/– transfers a hollow framework with a six-atom triangular prism unit. By comparing the geometry of neutral and anionic KMgn0/– 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 KMg90/– clusters. The spectroscopic properties based on the PES, IR and Raman spectra have also been discussed.