密度泛函理論研究鈥摻雜硅團簇的結(jié)構(gòu)和性質(zhì)
發(fā)布時間：2018-09-17 14:35
【摘要】：在硅團簇中摻雜稀土金屬元素,不但能使硅團簇的穩(wěn)定,而且還能作為一種擁有新特性(包括磁性、光學(xué)性質(zhì)、自旋電子和催化性等)的功能納米材料的基元,在新材料的設(shè)計領(lǐng)域中發(fā)揮著重要作用。本文主要以鑭系稀土金屬鈥(Ho)摻雜硅團簇HoSi_n(n=3-20)為研究對象,采用不同的密度泛函方法研究了其結(jié)構(gòu)與性質(zhì)的變化。對于小分子HoSi_n(n=3-9)及其陰離子體系,采用PBE,PBE0,B3LYP和mPW2PLYP四種密度泛函方法結(jié)合相對論效應(yīng)的小核贗勢基組(ECP28MWB)和cc-pVTZ基組得出以下結(jié)論:(1)含有MP2相關(guān)函的雙雜合mPW2PLYP方法最能準(zhǔn)確地預(yù)測HoSi_n(n=3-9)的基態(tài)結(jié)構(gòu)和性質(zhì)。對于中性分子預(yù)測的基態(tài)結(jié)構(gòu)是六重態(tài),且都是取代結(jié)構(gòu)(除了n=7)。對于陰離子預(yù)測的基態(tài)結(jié)構(gòu)都是五重態(tài)。(2)mPW2PLYP方法預(yù)測的電子親合能與實驗值能夠很好地符合,模擬的HoSi_n?(n=5 9)的光電子能譜和實驗光電子能譜也很好地符合。(3)從HoSi_n斷裂出Ho原子的斷裂能在n=4和n=7時為局域最小值,在n=5和n=8時為局域最大值。(4)HOMO-LUMO能隙表明摻雜稀土原子能明顯提高硅團簇的光化學(xué)反應(yīng)性。(5)自然布局分析表明HoSi_n(n=3-9)及其它們的陰離子的磁性主要由Ho原子提供,盡管Ho原子的4f電子參與成鍵,但是Ho原子的磁性并沒有消失。對于大分子HoSi_n(n=10-20)體系,采用B3LYP和PBE0兩種密度泛函方法結(jié)合cc-PVDZ基組和小核相對論基組(ECP28MWB)得出以下結(jié)論:(1)當(dāng)n=10-15時,HoSi_n被預(yù)測的基態(tài)結(jié)構(gòu)是四重態(tài)的取代結(jié)構(gòu)。當(dāng)n=16-20時,HoSi_n被預(yù)測的基態(tài)結(jié)構(gòu)為六重態(tài)的內(nèi)嵌籠形結(jié)構(gòu),并且HoSi16為最小籠型基態(tài)結(jié)構(gòu)。(2)從相對穩(wěn)定性來看,HoSi13,HoSi16,HoSi18和HoSi20比其他團簇更穩(wěn)定。(3)硬度分析表明將Ho原子摻雜到Sin團簇中能夠提高其光敏感型,特別是HoSi20。(4)從電荷轉(zhuǎn)移來看,對于HoSi_n(n=10-15)非籠形結(jié)構(gòu),電荷是從Ho原子轉(zhuǎn)移到Sin團簇,Ho是電子供體。對于HoSi_n(n=16-20)籠形結(jié)構(gòu),轉(zhuǎn)移方向是相反的,Ho是電子受體。(5)磁性分析表明HoSi_n團簇的大部分磁性由Ho原子提供,形成籠形結(jié)構(gòu)時磁性并沒有消失。對于HoSi_n(n=16-20)籠形結(jié)構(gòu),4f電子發(fā)生變化,參與成鍵。而且HoSi_n(n=16-20)團簇的總磁矩增加了。(6)籠形的HoSi16由于高化學(xué)穩(wěn)定性和相對穩(wěn)定性,最適合作為新型高密度磁存儲器納米材料的構(gòu)建基元。完全籠形的HoSi20團簇由于高相對穩(wěn)定性和光敏感性,最適合作為新型光學(xué)和光電光敏納米材料的構(gòu)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.
【學(xué)位授予單位】：內(nèi)蒙古工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O641.4
本文編號：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.
【學(xué)位授予單位】：內(nèi)蒙古工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O641.4
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2 劉玉真,羅成林;硅團簇的結(jié)構(gòu)及生長模式——緊束縛分子動力學(xué):Si_(11)—Si_(32)[J];物理學(xué)報;2004年02期
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