Systematic Theoretical Study on Structural, Stability, Electronic, and Spectral Properties of Si2MgQn(Q=0,±;n=1-11) Clusters of Silicon-Magnesium Sensor Material

Abstract

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 MgQn (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 MgQn (n = 1–11; Q = 0, ±1) clusters of silicon-magnesium sensor material are three-dimensional structures. Interestingly, although large size Si2 MgQn clusters show cage-like structures, silicon atoms are not in the center of the cage, but tend to the edge. The Si2 Mg-11,5,6,8 and Si2 Mg+11,3,4,7,9,10 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 Si2Mgn clusters decreases with the increase of magnesium atoms. The relative stabilities of neutral and charged Si2 MgQn (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 Mg03, Si2 Mg-13, and Si2 Mg+13 clusters have stronger stabilities than others. NCP and NEC analysis results show that the charges in Si2 MgQn (n = 1–11; Q = 0, ±1) clusters of silicon-magnesium sensor material transfer from Mg atoms to Si atoms except for Si2 (Mg+11, and strong sp hybridizations are presented in Si atoms of Si2 MgQn clusters. Finally, the infrared (IR) and Raman spectra of all ground state of Si2MgQn (n = 1–11; Q = 0, ±1) clusters of silicon magnesium sensor material are also discussed.