密度泛函理论研究镨掺杂硅团簇的结构和性质
发布时间：2018-10-21 11:27
【摘要】：在硅团簇中掺杂稀土金属元素不仅可以提高硅团簇的稳定性,还可以表现出磁性等新的性质。稀土金属-硅团簇可以作为新的功能材料的构建单元,在新材料设计领域中有着极为重要的价值。本文采用不同的密度泛函方法,分别系统地研究了稀土金属镨掺杂的硅团簇Pr Si_n(n=3 9)及其阴离子和Pr Si_n(n=10 21)中性分子的结构和性质。在B3LYP,PBE0和m PW2PLYP水平下结合aug-SEG/ECP基组,对Pr Si_n(n=3 9)中性分子及其阴离子的几何结构和性质如绝热电子亲和能,模拟的光电子能谱,稳定性,HOMO-LUMO能隙,电荷转移和磁性进行了详细研究。研究结果表明含有MP2相关函的双杂合m PW2PLYP方法可以准确地预测Pr原子掺杂硅团簇的基态结构和性质,具体结果如下:(1)从n=7开始,Pr Si_n(n=3 9)阴离子团簇的基态结构不属于取代结构。中性的基态结构结合一个电子后,基态结构中额外的电子效应非常强烈。Pr Si3-,Pr Si6-和Pr Si8-团簇的基态结构不同于其中性团簇。(2)预测的Pr Si_n(n=3 9)的电子亲合能的平均绝对误差仅为0.05 e V。最大误差为0.10 e V。(3)实验的光电子能谱与理论模拟结果一致,表明预测的Pr Si_n-(n=4 9)团簇的基态结构是可信的。(4)根据模拟光电子能谱和理论计算的电子亲合能,我们重新分配了PrSi_4~-的实验光电子能谱,得到了PrSi_4~-电子亲合能的实验值为2.0±0.1 e V,不是1.6±0.1 e V。(5)计算了从Pr Si_n断裂出Pr原子的断裂能。(6)HOMO-LUMO能隙表明掺杂稀土原子能明显提高硅团簇的光化学反应性,但提高的光化学反应性效应不如Eu和Sm原子掺杂在硅团簇中的好。(7)自然布居分析表明中性Pr Si_n及其阴离子中(除Pr Si3外)其4f电子参与成键,但Pr原子的磁性没有消失,Pr Si_n的大部分磁性由Pr原子提供。在B3LYP和PBE0水平下结合SEG/ECP基组,系统地研究了Pr Si_n(n=10 21)中性分子的几何结构和性质。研究结果表明:(1)由Si原子的cc-p VTZ和cc-p VDZ基组进行构型优化后获得的基态结构相同。(2)从n=20开始,Pr Si_n基态结构预测为内嵌的笼形结构,即Pr Si20为Pr Si_n最小笼型基态结构。(3)稳定性分析的结果表明Pr Si11,Pr Si13,Pr Si16和Pr Si20比其它团簇更稳定,特别是Pr Si20构型。(4)HOMO-LUMO能隙分析表明,在纯Si_n(n=10 21)团簇中掺杂Pr原子可提高团簇的光化学敏感性,尤其是Pr Si20结构。(5)电荷转移和磁性分析可以看出,Pr Si_n的大部分磁性由Pr原子提供,形成笼形结构时磁性并没有消失。Pr原子的4f电子参与成键,它的一个电子从4f轨道转移到5d轨道。在非笼形团簇中,Pr原子是电子供体;当形成笼形结构时,Pr原子是电子受体。Pr Si20结构中的Pr原子与硅团簇之间的成键性质本质上为离子键,且成键作用非常强。
[Abstract]:Doping rare earth elements into silicon clusters can not only improve the stability of silicon clusters, but also exhibit new properties such as magnetic properties. Rare earth metal-silicon clusters can be used as building units of new functional materials, which are of great value in the field of new materials design. In this paper, the structure and properties of praseodymium doped silicon clusters (Pr Si_n (nd3) 9) and their anions and neutral molecules (Pr Si_n (nn10 / 21) have been systematically studied by using different density functional methods (DFT). The geometric structure and properties of neutral molecules and their anions of Pr Si_n (nun3 + 9) have been studied in detail at the level of B3LYPX PBE0 and m PW2PLYP, such as adiabatic electron affinity, simulated photoelectron spectroscopy, stability, HOMO-LUMO gap, charge transfer and magnetism. The results show that the double hybrid m PW2PLYP method with MP2 correlation function can accurately predict the ground state structure and properties of Pr atom doped silicon clusters. The results are as follows: (1) the ground state structure of Pr Si_n (nni3 + 9) anion cluster does not belong to the substitution structure. When the neutral ground state structure binds to one electron, the extra electron effect in the ground state structure is very strong. The ground state structure of Pr Si3-,Pr Si6- and Pr Si8- clusters is different from that of their neutral cluster. (2) the average absolute error of the predicted electron affinity energy of Pr Si_n (NN3 + 9) is only 0. 05 EV. The maximum error is 0.10 e V. (_ 3) the photoelectron spectroscopy of the experiment is consistent with the theoretical simulation results, which indicates that the predicted ground state structure of the Pr Si_n- (nni4) cluster is credible. (4) the electron affinity energy calculated according to the simulated photoelectron spectroscopy and the theoretical calculation. We've reallocated PrSi_4~- 's experimental photoelectron spectroscopy, The experimental value of PrSi_4~- electron affinity energy is 2. 0 卤0. 1 EV, not 1. 6 卤0. 1 e V. (5. The fracture energy of Pr atom is calculated from Pr Si_n. (6) the HOMO-LUMO gap shows that doped rare earth atomic energy can obviously improve the photochemical reaction of Si cluster. But the enhanced photochemical reactivity effect is not as good as that of Eu and Sm atoms doping in silicon clusters. (7) Natural population analysis shows that 4f electrons in neutral Pr Si_n and its anions (except Pr Si3) participate in bonding. But the magnetism of the Pr atom has not disappeared, and most of the magnetism of the Pr Si_n atom is provided by the Pr atom. The geometric structure and properties of neutral molecules of Pr Si_n (n ~ (10) ~ (21) have been systematically studied at the level of B3LYP and PBE0 combined with the SEG/ECP basis set. The results show that: (1) the ground state structure obtained by the configuration optimization of the cc-p VTZ and cc-p VDZ basis sets of Si atoms is the same. (2) starting from NW 20, the ground state structure of Pr Si_n is predicted to be an embedded cage structure. That is, Pr Si20 is the smallest cage ground state structure of Pr Si_n. (3) the results of stability analysis show that Pr Si11,Pr Si13,Pr Si16 and Pr Si20 are more stable than other clusters, especially the Pr Si20 configuration. (4) the band gap analysis of HOMO-LUMO shows that, Doping of Pr atoms in pure Si_n (nni10 ~ (21) clusters can enhance the photochemical sensitivity of the clusters, especially the Pr Si20 structure. (5) charge transfer and magnetic analysis show that most of the magnetic properties of Pr Si_n are supplied by Pr atoms. The magnetic properties do not disappear when the cage structure is formed. The 4f electrons of the Pr atom take part in bonding, and one of its electrons is transferred from the 4f orbital to the 5d orbital. In non-caged clusters, the Pr atom is an electron donor, while the Pr atom is an electron receptor when the cage structure is formed. The bonding property between the Pr atom and the silicon cluster in the Pr Si20 structure is essentially ionic bond, and the bonding effect is very strong.
【学位授予单位】：内蒙古工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O641.1
本文编号：2284959
[Abstract]:Doping rare earth elements into silicon clusters can not only improve the stability of silicon clusters, but also exhibit new properties such as magnetic properties. Rare earth metal-silicon clusters can be used as building units of new functional materials, which are of great value in the field of new materials design. In this paper, the structure and properties of praseodymium doped silicon clusters (Pr Si_n (nd3) 9) and their anions and neutral molecules (Pr Si_n (nn10 / 21) have been systematically studied by using different density functional methods (DFT). The geometric structure and properties of neutral molecules and their anions of Pr Si_n (nun3 + 9) have been studied in detail at the level of B3LYPX PBE0 and m PW2PLYP, such as adiabatic electron affinity, simulated photoelectron spectroscopy, stability, HOMO-LUMO gap, charge transfer and magnetism. The results show that the double hybrid m PW2PLYP method with MP2 correlation function can accurately predict the ground state structure and properties of Pr atom doped silicon clusters. The results are as follows: (1) the ground state structure of Pr Si_n (nni3 + 9) anion cluster does not belong to the substitution structure. When the neutral ground state structure binds to one electron, the extra electron effect in the ground state structure is very strong. The ground state structure of Pr Si3-,Pr Si6- and Pr Si8- clusters is different from that of their neutral cluster. (2) the average absolute error of the predicted electron affinity energy of Pr Si_n (NN3 + 9) is only 0. 05 EV. The maximum error is 0.10 e V. (_ 3) the photoelectron spectroscopy of the experiment is consistent with the theoretical simulation results, which indicates that the predicted ground state structure of the Pr Si_n- (nni4) cluster is credible. (4) the electron affinity energy calculated according to the simulated photoelectron spectroscopy and the theoretical calculation. We've reallocated PrSi_4~- 's experimental photoelectron spectroscopy, The experimental value of PrSi_4~- electron affinity energy is 2. 0 卤0. 1 EV, not 1. 6 卤0. 1 e V. (5. The fracture energy of Pr atom is calculated from Pr Si_n. (6) the HOMO-LUMO gap shows that doped rare earth atomic energy can obviously improve the photochemical reaction of Si cluster. But the enhanced photochemical reactivity effect is not as good as that of Eu and Sm atoms doping in silicon clusters. (7) Natural population analysis shows that 4f electrons in neutral Pr Si_n and its anions (except Pr Si3) participate in bonding. But the magnetism of the Pr atom has not disappeared, and most of the magnetism of the Pr Si_n atom is provided by the Pr atom. The geometric structure and properties of neutral molecules of Pr Si_n (n ~ (10) ~ (21) have been systematically studied at the level of B3LYP and PBE0 combined with the SEG/ECP basis set. The results show that: (1) the ground state structure obtained by the configuration optimization of the cc-p VTZ and cc-p VDZ basis sets of Si atoms is the same. (2) starting from NW 20, the ground state structure of Pr Si_n is predicted to be an embedded cage structure. That is, Pr Si20 is the smallest cage ground state structure of Pr Si_n. (3) the results of stability analysis show that Pr Si11,Pr Si13,Pr Si16 and Pr Si20 are more stable than other clusters, especially the Pr Si20 configuration. (4) the band gap analysis of HOMO-LUMO shows that, Doping of Pr atoms in pure Si_n (nni10 ~ (21) clusters can enhance the photochemical sensitivity of the clusters, especially the Pr Si20 structure. (5) charge transfer and magnetic analysis show that most of the magnetic properties of Pr Si_n are supplied by Pr atoms. The magnetic properties do not disappear when the cage structure is formed. The 4f electrons of the Pr atom take part in bonding, and one of its electrons is transferred from the 4f orbital to the 5d orbital. In non-caged clusters, the Pr atom is an electron donor, while the Pr atom is an electron receptor when the cage structure is formed. The bonding property between the Pr atom and the silicon cluster in the Pr Si20 structure is essentially ionic bond, and the bonding effect is very strong.
【学位授予单位】：内蒙古工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O641.1
【参考文献】
相关期刊论文 前1条
1 白燕枝;赵高峰;沈学锋;孙建敏;王渊旭;;TbSi_n(n=2-13)团簇的结构、电子及磁学性质(英文)[J];物理化学学报;2011年01期
，本文编号：2284959
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