A DFT study on structural evolution, electronic property and spectral analysis of yttrium-doped germanium clusters

The structural evolution, electronic property and spectral analysis of YGe<i>_n</i>^q (<i>n </i>= 4–20, <i>q</i> = 0, −1) has been examined under the framework of density functional theory combined with the Artificial Bees Colony and the Saunders ‘Kick’ algorithm. The global minimum structure of the YGe<i>_n</i>^- cluster is recognised by contrasting the simulated and measured photoelectron spectra (PES). Average binding energies, second difference energies, highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gaps are shown as size change and display abnormal stability at <i>n </i>= 16. Natural population analysis (NPA) shows the charge transfer from Ge to Y atom is 4.62 e in YGe₁₆^-, forming ionic bonds. HOMO–LUMO orbitals are mainly composed of Ge atoms. Electron localisation function (ELF) reveals the electrostatic force between Y and Ge atoms and the covalent interaction between each two Ge atoms, which is in accordance with the bond analysis. The current work shows that YGe₁₆^- is viewed as a promising building block for rare earth-doped semiconductor materials.