Systematic Theoretical Study on Structural, Stability, Electronic, and Spectral Properties of Si₂ (Q = 0, ±1; n =...

By using CALYPSO searching method and Density Functional Theory (DFT) method at the B3LYP/6-311G (d) level of cluster method, a systematic study of the structures, stabilities, electronic and spectral properties of Si₂ $$ (n = 1-11; Q = 0, ±1) clusters of silicon-magnesium sensor material, is performed. According to the calculations, it was found that when n > 4, most stable isomers in Si₂ $$ (n = 1-11; Q = 0, ±1) clusters of silicon-magnesium sensor material are three-dimensional structures. Interestingly, although large size Si₂ $$ clusters show cage-like structures, silicon atoms are not in the center of the cage, but tend to the edge. The Si₂ $$ and Si₂ $$ clusters obviously differ to their corresponding neutral structures, which are in good agreement with the calculated values of VIP, AIP, VEA, and AEA. |VIP-VEA| values reveal that the hardness of Si₂Mg_n clusters decreases with the increase of magnesium atoms. The relative stabilities of neutral and charged Si₂ $$ (n = 1-11; Q = 0, ±1) clusters of silicon-magnesium sensor material is analyzed by calculating the average binding energy, fragmentation energy, second-order energy difference and HOMO-LUMO gaps. The results reveal that the Si₂ $$ , Si₂ $$ , and Si₂ $$ clusters have stronger stabilities than others. NCP and NEC analysis results show that the charges in Si₂ $$ (n = 1-11; Q = 0, ±1) clusters of silicon-magnesium sensor material transfer from Mg atoms to Si atoms except for Si₂ $$ , and strong sp hybridizations are presented in Si atoms of Si₂ $$ clusters. Finally, the infrared (IR) and Raman spectra of all ground state of Si₂ $$ (n = 1-11; Q = 0, ±1) clusters of silicon magnesium sensor material are also discussed.