Systematic Theoretical Study on Structural, Stability, Electronic, and Spectral Properties of Si2MgnQ (Q = 0, ±1; n = 1–11) Clusters of Silicon-Magnesium Sensor Material

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 Si 2 Mg n Q ( 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 Si 2 Mg n Q ( n = 1–11; Q = 0, ±1) clusters of silicon-magnesium sensor material are three-dimensional structures. Interestingly, although large size Si 2 Mg n Q clusters show cage-like structures, silicon atoms are not in the center of the cage, but tend to the edge. The Si 2 Mg 1 , 5 , 6 , 8 - 1 and Si 2 Mg 13 , 4 , 7 , 9 , 10 + 1 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 Si 2 Mg n clusters decreases with the increase of magnesium atoms. The relative stabilities of neutral and charged Si 2 Mg n Q ( 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 Si 2 Mg 3 0 , Si 2 Mg 3 - 1 , and Si 2 Mg 3 + 1 clusters have stronger stabilities than others. NCP and NEC analysis results show that the charges in Si 2 Mg n Q ( n = 1–11; Q = 0, ±1) clusters of silicon-magnesium sensor material transfer from Mg atoms to Si atoms except for Si 2 Mg 1 + 1 , and strong sp hybridizations are presented in Si atoms of Si 2 Mg n Q clusters. Finally, the infrared (IR) and Raman spectra of all ground state of Si 2 Mg n Q ( n = 1–11; Q = 0, ±1) clusters of silicon magnesium sensor material are also discussed.