密度泛函理论研究钬掺杂硅团簇的结构和性质
发布时间：2018-09-17 14:35
【摘要】：在硅团簇中掺杂稀土金属元素,不但能使硅团簇的稳定,而且还能作为一种拥有新特性(包括磁性、光学性质、自旋电子和催化性等)的功能纳米材料的基元,在新材料的设计领域中发挥着重要作用。本文主要以镧系稀土金属钬(Ho)掺杂硅团簇HoSi_n(n=3-20)为研究对象,采用不同的密度泛函方法研究了其结构与性质的变化。对于小分子HoSi_n(n=3-9)及其阴离子体系,采用PBE,PBE0,B3LYP和mPW2PLYP四种密度泛函方法结合相对论效应的小核赝势基组(ECP28MWB)和cc-pVTZ基组得出以下结论:(1)含有MP2相关函的双杂合mPW2PLYP方法最能准确地预测HoSi_n(n=3-9)的基态结构和性质。对于中性分子预测的基态结构是六重态,且都是取代结构(除了n=7)。对于阴离子预测的基态结构都是五重态。(2)mPW2PLYP方法预测的电子亲合能与实验值能够很好地符合,模拟的HoSi_n?(n=5 9)的光电子能谱和实验光电子能谱也很好地符合。(3)从HoSi_n断裂出Ho原子的断裂能在n=4和n=7时为局域最小值,在n=5和n=8时为局域最大值。(4)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。(5)自然布局分析表明HoSi_n(n=3-9)及其它们的阴离子的磁性主要由Ho原子提供,尽管Ho原子的4f电子参与成键,但是Ho原子的磁性并没有消失。对于大分子HoSi_n(n=10-20)体系,采用B3LYP和PBE0两种密度泛函方法结合cc-PVDZ基组和小核相对论基组(ECP28MWB)得出以下结论:(1)当n=10-15时,HoSi_n被预测的基态结构是四重态的取代结构。当n=16-20时,HoSi_n被预测的基态结构为六重态的内嵌笼形结构,并且HoSi16为最小笼型基态结构。(2)从相对稳定性来看,HoSi13,HoSi16,HoSi18和HoSi20比其他团簇更稳定。(3)硬度分析表明将Ho原子掺杂到Sin团簇中能够提高其光敏感型,特别是HoSi20。(4)从电荷转移来看,对于HoSi_n(n=10-15)非笼形结构,电荷是从Ho原子转移到Sin团簇,Ho是电子供体。对于HoSi_n(n=16-20)笼形结构,转移方向是相反的,Ho是电子受体。(5)磁性分析表明HoSi_n团簇的大部分磁性由Ho原子提供,形成笼形结构时磁性并没有消失。对于HoSi_n(n=16-20)笼形结构,4f电子发生变化,参与成键。而且HoSi_n(n=16-20)团簇的总磁矩增加了。(6)笼形的HoSi16由于高化学稳定性和相对稳定性,最适合作为新型高密度磁存储器纳米材料的构建基元。完全笼形的HoSi20团簇由于高相对稳定性和光敏感性,最适合作为新型光学和光电光敏纳米材料的构建基元。
[Abstract]:Doping rare earth elements into silicon clusters can not only stabilize the silicon clusters, but also act as a functional nanomaterial with new properties (including magnetic, optical, spin electron and catalytic properties). It plays an important role in the design of new materials. In this paper, the structure and properties of lanthanide rare earth metal holmium: holmium (Ho) doped silicon cluster HoSi_n (nb3-20) are studied by using different density functional methods. For the small molecule HoSi_n (nnc3-9) and its anion system, Four density functional methods, PBE,PBE0,B3LYP and mPW2PLYP, combined with relativistic pseudopotential basis sets (ECP28MWB) and cc-pVTZ basis sets, are used to obtain the following conclusions: (1) the double hybrid mPW2PLYP method with MP2 correlation functions can best predict the ground state structure and properties of HoSi_n (nc-9). For neutral molecules, the predicted ground state structure is a six-fold structure, and all of them are substituted structures (except for N7). For anion, the ground state structure is quintupled. (2) the electron affinity energy predicted by mPW2PLYP method is in good agreement with the experimental data. The photoelectron spectra of the simulated HoSi_n? (nni5 / 9) are also in good agreement with the experimental photoelectron spectra. (3) the fracture energies of the Ho atoms from the HoSi_n fracture are the local minimum values of nn 4 and n = 7, respectively. (4) the HOMO-LUMO gap indicates that doped rare earth atoms can significantly improve the photochemical reactivity of silicon clusters. (5) the natural layout analysis shows that the magnetic properties of HoSi_n (nni3-9) and their anions are mainly supplied by Ho atoms. Although the 4 f electrons of the Ho atom are involved in bonding, the magnetism of the Ho atom has not disappeared. For the macromolecular HoSi_n (n ~ (10 ~ (-20) system, B3LYP and PBE0 density functional methods are used to combine the cc-PVDZ basis set and the small nuclear relativistic basis set (ECP28MWB). The following conclusions are obtained: (1) the predicted ground state structure of HoSin is a quaternary substitute structure when n ~ (10 ~ (-15) is applied to the cc-PVDZ base set and the small nucleus relativistic basis set (ECP28MWB). When n is 16-20, the predicted ground state structure of HoSiS _ n is a caged structure with a six-fold state. Moreover, HoSi16 is the smallest cage ground state structure. (2) HoSi13 HoSi16 HoSi18 and HoSi20 are more stable than other clusters in terms of relative stability. (3) hardness analysis shows that doping Ho atoms into Sin clusters can improve their photosensitivity, especially HoSi20. (4) from the point of view of charge transfer. For the non-cage structure of HoSi_n (nni10-15), the charge is transferred from the Ho atom to the Sin cluster Ho is an electron donor. For the cage structure of HoSi_n (nni-16-20), the transfer direction is opposite. (5) the magnetic analysis shows that most of the magnetic properties of the HoSi_n cluster are supplied by the Ho atom, and the magnetism does not disappear when the cage structure is formed. For the HoSi_n (n ~ (16 ~ (- 20) cage structure, the 4f electrons change and participate in bond formation. Moreover, the total magnetic moment of HoSi_n (nni16-20) clusters increases. (6) because of its high chemical stability and relative stability, HoSi16 is the most suitable element for the construction of novel high-density magnetic memory nanomaterials. Due to its high relative stability and light sensitivity, the completely caged HoSi20 cluster is the most suitable element for the construction of novel optical and optoelectronic Guang Min nanomaterials.
【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】：O641.4
本文编号：2246228
[Abstract]:Doping rare earth elements into silicon clusters can not only stabilize the silicon clusters, but also act as a functional nanomaterial with new properties (including magnetic, optical, spin electron and catalytic properties). It plays an important role in the design of new materials. In this paper, the structure and properties of lanthanide rare earth metal holmium: holmium (Ho) doped silicon cluster HoSi_n (nb3-20) are studied by using different density functional methods. For the small molecule HoSi_n (nnc3-9) and its anion system, Four density functional methods, PBE,PBE0,B3LYP and mPW2PLYP, combined with relativistic pseudopotential basis sets (ECP28MWB) and cc-pVTZ basis sets, are used to obtain the following conclusions: (1) the double hybrid mPW2PLYP method with MP2 correlation functions can best predict the ground state structure and properties of HoSi_n (nc-9). For neutral molecules, the predicted ground state structure is a six-fold structure, and all of them are substituted structures (except for N7). For anion, the ground state structure is quintupled. (2) the electron affinity energy predicted by mPW2PLYP method is in good agreement with the experimental data. The photoelectron spectra of the simulated HoSi_n? (nni5 / 9) are also in good agreement with the experimental photoelectron spectra. (3) the fracture energies of the Ho atoms from the HoSi_n fracture are the local minimum values of nn 4 and n = 7, respectively. (4) the HOMO-LUMO gap indicates that doped rare earth atoms can significantly improve the photochemical reactivity of silicon clusters. (5) the natural layout analysis shows that the magnetic properties of HoSi_n (nni3-9) and their anions are mainly supplied by Ho atoms. Although the 4 f electrons of the Ho atom are involved in bonding, the magnetism of the Ho atom has not disappeared. For the macromolecular HoSi_n (n ~ (10 ~ (-20) system, B3LYP and PBE0 density functional methods are used to combine the cc-PVDZ basis set and the small nuclear relativistic basis set (ECP28MWB). The following conclusions are obtained: (1) the predicted ground state structure of HoSin is a quaternary substitute structure when n ~ (10 ~ (-15) is applied to the cc-PVDZ base set and the small nucleus relativistic basis set (ECP28MWB). When n is 16-20, the predicted ground state structure of HoSiS _ n is a caged structure with a six-fold state. Moreover, HoSi16 is the smallest cage ground state structure. (2) HoSi13 HoSi16 HoSi18 and HoSi20 are more stable than other clusters in terms of relative stability. (3) hardness analysis shows that doping Ho atoms into Sin clusters can improve their photosensitivity, especially HoSi20. (4) from the point of view of charge transfer. For the non-cage structure of HoSi_n (nni10-15), the charge is transferred from the Ho atom to the Sin cluster Ho is an electron donor. For the cage structure of HoSi_n (nni-16-20), the transfer direction is opposite. (5) the magnetic analysis shows that most of the magnetic properties of the HoSi_n cluster are supplied by the Ho atom, and the magnetism does not disappear when the cage structure is formed. For the HoSi_n (n ~ (16 ~ (- 20) cage structure, the 4f electrons change and participate in bond formation. Moreover, the total magnetic moment of HoSi_n (nni16-20) clusters increases. (6) because of its high chemical stability and relative stability, HoSi16 is the most suitable element for the construction of novel high-density magnetic memory nanomaterials. Due to its high relative stability and light sensitivity, the completely caged HoSi20 cluster is the most suitable element for the construction of novel optical and optoelectronic Guang Min nanomaterials.
【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】：O641.4
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