Theoretical Insights into the Geometrical Evolution, Photoelectron Spectra, and Vibrational Properties of YGe_<i>n</i>^– (<i>n</i> = 6–20) Anions: From Y-Linked to Y-Encapsulated Structures

Abstract

The structural evolution behavior of germanium anionic clusters doped with the rare-earth metal yttrium, YGe _<i>n</i> ^- (<i>n</i> = 6-20), has been investigated using a mPW2PLYP density functional scheme and an ABCluster structure searching technique. The results reveal that with increasing cluster size <i>n</i>, the structure evolution pattern is from the Y-linked framework (<i>n</i> = 10-14), where Y serves as a linker (the Y atom bridges two germanium subclusters), to the Y-encapsulated framework (<i>n</i> = 15-20), where the Y atom is located in the center of the Ge cage. The simulated PES spectra show satisfying agreement with the experimental PES spectra for <i>n</i> = 12-20, which reveals that the global minimum structures reported here are reliable. In particular, the anionic YGe₁₆ ^- nanocluster is found to be the most stable structure in the size range of <i>n</i> = 6-20 through analyzes of the relative stability, highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap, spherical jellium model, and isochemical shielding surface. Moreover, spectral properties such as infrared and Raman spectra were reported. In addition, the UV-vis spectra of the YGe₁₆ ^- nanocluster are in good agreement with solar energy distribution, showing that such substances serve as multifunctional building blocks to be potentially used in optoelectronic devices or solar energy converters.