Structural and Electronic Properties of Bimetallic Eu2 Doped Silicon-Based Clusters

The rare earth metal doped Si-based semiconductor clusters have aroused increased attention in a lot of fields. Here, the structural evolution, magnetic and spectral properties of bimetallic Eu-2 doped silicon-based clusters, Eu2Sin- (1 & LE; n & LE; 12), have been investigated using artificial bees colony and Saunders "Kick" global optimization techniques associated with density-functional theory calculations. The calculations show that the two Eu atoms prefer to occupy the surface position of parent silicon clusters and form exohedral geometric structures. It is found that the structural growth pattern is reflected at n = 4-8 where the two Eu atoms lie on the framework of distorted pentagon. Eu2Si5- is determined to the most stable cluster owing to the strong interaction between host Si atoms and dual Eu atoms. The natural atomic orbital method reveals that the charges always transfer from the Eu to Si parent atoms. Interestingly, the total magnetic moments are not quenched but superimposed together with introduction into Si-based cluster, 4f electrons almost remain in two Eu atoms and hardly participate in the molecular Si-Eu bonding. Moreover, theoretical photoelectron spectra are predicted in order to provide a theoretical guidance for the future photoelectron spectroscopy experiments of double rare earth metal doped Si-based semiconductor clusters.