Structural, Electronic, and Nonlinear Optical Characteristics of Europium-Doped Germanium Anion Nanocluster EuGen− (n = 7–20): A Theoretical Investigation

Doping rare-earth metals into semiconductor germanium clusters can significantly enhance the stability of these clusters while introducing novel and noteworthy optical properties. Herein, a series of EuGe<i>_n</i>^- (<i>n</i> = 7-20) clusters and their structural and nonlinear optical properties are investigated via the ABCluster global search technique combined with the double-hybrid density functional theory mPW2PLYP. The structure growth pattern can be divided into two stages: an adsorption structure and a linked structure (when <i>n</i> = 7-10 and <i>n</i> = 11-20, respectively). In addition to simulating the photoelectron spectra of the clusters, their various properties, including their (hyper)polarizability, magnetism, charge transfer, relative stability, and energy gap, are identified. According to our examination, the EuGe₁₃^- cluster exhibits a significant nonlinear optical response of the <i>β</i>_tot value of 7.47 × 10⁵ a.u., and is thus considered a promising candidate for outstanding nonlinear optical semiconductor nanomaterials.