The effect of silicon doping on the geometrical structures, stability, and electronic and spectral properties of magnesium clusters: DFT study of SiMg_n (n = 1‐12) clusters

Abstract

Using the density functional theory (DFT) method at the B3LYP /6−311G (D) level, we studied how silicon doping affects the geometrical structure, stability, and electronic and spectral properties of magnesium clusters. The stable isomers of SiMg n (n = 1‐12) clusters were calculated by searching numerous initial configurations using the CALYPSO program. The geometrical structure optimization shows that most stable SiMg n (n = 3‐12) clusters are three‐dimensional. In addition, geometrical structure growth patterns show that some structures of SiMg n clusters can be directly formed by replacing one Mg atom in the corresponding Mg n + 1 cluster with one silicon atom, such as SiMg8 and Mg9 clusters. The stability of SiMg n clusters is analyzed by calculating the average binding energy, fragmentation energy, and second‐order energy difference. The results show that SiMg n clusters with n = 5 and 8 are more stable than others. MO contents analysis show that the Si 3p‐orbitals and Mg 3s‐orbital are mainly responsible for the stability of these two clusters. The results of the natural charge population (NCP) and natural electronic configure (NEC) analysis of the electronic properties reveal that the charges in SiMgn (n = 1‐12) clusters transfer from magnesium atoms to silicon frame, and electronic charge distributions are primarily governed by s‐ and p‐orbital interactions. In addition, the Vertical ionization potential (VIP), vertical electron affinity (VEA), and chemical hardness of ground sates of SiMg n (n = 1‐12) clusters were studied in detail and compared with the experimental results. The conclusions show that the chemical hardness of most SiMg n clusters are lower than that of pure Mg n + 1 (n = 1‐12) clusters, except for n = 1 and 8. This indicates that the doping of silicon atom can always reduce the chemical hardness of pure magnesium clusters. Finally, the infrared and Raman spectral properties of SiMg5 and SiMg8 clusters were calculated and discussed in detail.

Computational Exploration on the Structural and Optical Properties of Gold-Doped Alkaline-Earth Magnesium AuMgn (n = 2–12) Nanoclusters: DFT Study

“…In conclusion, based on the small size of AuMg n-1 or smaller, AuMg n ( n = 2–12) nanoclusters can usually be formed by adsorption of Mg atoms in different directions, and the interesting point is that the direction of adsorption does not have a fixed pattern. Such result is consistent with many existed Mg-based nanoclusters reported ( Li et al, 2017 ; Zeng et al, 2020 , 2021 ; Zhu et al, 2020 ). However, despite the many similarities, the structures of gold-doped Mg nanoclusters have unique properties compared to other Mg-based nanoclusters studies.…”

“…However, despite the many similarities, the structures of gold-doped Mg nanoclusters have unique properties compared to other Mg-based nanoclusters studies. For example, the structure of AuMg 3 nanoclusters is 2D planar, while the lowest energy heterostructures of Be ( Zeng et al, 2020 ), Si ( Zhu et al, 2020 ), C, Ge, Sn ( Zeng et al, 2021 ), Zn-doped ( Li et al, 2017 ) Mg nanoclusters of corresponding sizes are all ortho-tetrahedral in shape. Interestingly, although the ground-state structures of AuMg 9 and BeMg 9 ( Zeng et al, 2020 ) look similar, the significant difference between them is that the Au atom locates on the surface of AuMg 9 while the Be atom is absorbed into the inside of BeMg 9 .…”

Probing on the Stable Structure of Silicon-Doped Charged Magnesium Nanomaterial Sensor: SiMgn±1 (N = 2−12) Clusters DFT Study

“…Compared with the research results of the local most stable neutral silicon-doped magnesium clusters (Zhu et al, 2020), we can find some interesting conclusions. First of all, whether silicon-doped magnesium clusters are neutral or charged, their local most stable clusters are composed of one silicon and eight magnesium atoms.…”

“…When the research interest in magnesium silicide sensors is transferred to the nanometer size, it becomes very necessary to use cluster methods to study silicon-doped magnesium clusters. Surprisingly, to our best knowledge, except for our previous work on silicon doped neutral magnesium clusters (Zhu et al, 2020), few studies have been made on silicon-doped charged magnesium alloy nanomaterials. In addition, the physical and chemical properties of the clusters will vary with their size and charge.…”

Quantum Chemistry Study on the Structures and Electronic Properties of Bimetallic Ca2-Doped Magnesium Ca2Mgn (n = 1–15) Clusters

“…Most recently, research found that heteroatom doping is an effective strategy to stabilize geometrical structures or to tune electronic properties. Up to now, based on the different quantum chemistry calculations, studies on metal-doped (Be, Al, Ge, Sn, 3 d and 4 d TM atoms) and nonmetal-doped (B, C, N, O, F and Si) magnesium clusters have harvested many great achievements [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. More importantly, based on the CALYPSO structural searching method and DFT, the structures and electronic properties of Be-, Be 2 -, Sr 2 - and Ba 2 -atom-doped differently sized magnesium clusters have been systemically discussed by Zeng’s, Zhao’s and our groups [ 33 , 34 , 35 , 36 , 37 ].…”