本文選題：恒溫分子動(dòng)力學(xué) + 團(tuán)簇�。� 參考：《新疆大學(xué)》2017年碩士論文

【摘要】：本文基于恒溫分子動(dòng)力學(xué)和第一性原理的密度泛函理論(Density Functional Theory,DFT)計(jì)算了如下三部分內(nèi)容:(1)不同尺寸不同組分的Au-Pd,Au-Ag和Au-Pt雙金屬團(tuán)簇的退火行為。(2)純金屬團(tuán)簇(Au_(13)和Pt_(13))及混合金屬團(tuán)簇(Au_(12)Pt和Pt_(12)Au)的幾何結(jié)構(gòu)和電子特性。(3)Rh_n(n=6、7)團(tuán)簇的基態(tài)結(jié)構(gòu)特征,以及在Rh_n(n=6、7)團(tuán)簇上吸附小分子(H_2、O_2、N_2、NO、CO、NO_2、CO_2、N_2O)體系的基態(tài)結(jié)構(gòu)和電子特性。得出的主要結(jié)論如下:(1)雙金屬Au-Pd和Au-Pt團(tuán)簇在發(fā)生退火行為時(shí),其Au原子會(huì)發(fā)生偏析行為:當(dāng)Au原子比重少于Pd或Pt原子時(shí),Au原子傾向于占據(jù)表面;當(dāng)兩者比重接近時(shí),Au原子則絕大部分占據(jù)團(tuán)簇表面。在雙金屬Au-Ag團(tuán)簇中,會(huì)發(fā)生Ag原子的偏析,其偏析行為與Au-Pd(Au-Pt)團(tuán)簇中的Au原子類似。在Au-Pt雙金屬團(tuán)簇中,隨著Au原子比重的增大,其δ-CV曲線將由無(wú)序變?yōu)橛行颉?2)基于第一性原理的DFT計(jì)算了純金屬團(tuán)簇(Au_(13)和Pt_(13))及混合金屬團(tuán)簇(Au_(12)Pt和Pt_(12)Au)的幾何結(jié)構(gòu)和電子特性。得到的結(jié)果表明:找到了Pt_(13)團(tuán)簇新的基態(tài)候選者,13個(gè)原子的純金屬團(tuán)簇存在明顯的低能同分異構(gòu)現(xiàn)象(特別是Au_(13)團(tuán)簇),但是通過(guò)摻雜Au(Pt)元素可抑制原團(tuán)簇的同分異構(gòu)現(xiàn)象;在計(jì)算垂直電離能(Vertical Ionization Potential,VIP)和垂直電子親和勢(shì)(Vertical Electron Affinities,VEA)時(shí)發(fā)現(xiàn),Au_(13)團(tuán)簇的VIP和VEA的值與實(shí)驗(yàn)值及其相近(存在相對(duì)論的情況下),摻雜對(duì)VIP和VEA的影響較小,但是摻雜可以改變團(tuán)簇費(fèi)米能處d電子的分布,團(tuán)簇費(fèi)米能處的d電子分布情況可能與其催化活性相關(guān)。(3)采用第一性原理的DFT計(jì)算研究了Rh_n(n=6、7)團(tuán)簇的基態(tài)結(jié)構(gòu)特性以及Rh_n(n=6、7)團(tuán)簇吸附小分子氣體(H_2、O_2、N_2、NO、CO、NO_2、CO_2,N_2O)基態(tài)幾何結(jié)構(gòu)和電子結(jié)構(gòu)特性。計(jì)算結(jié)果表明:Rh6團(tuán)簇的基態(tài)結(jié)構(gòu)的對(duì)稱性為Oh且不存在低能同分異構(gòu)體;Rh7團(tuán)簇基態(tài)結(jié)構(gòu)存在競(jìng)爭(zhēng)性。在Rh6團(tuán)簇上發(fā)生物理吸附的氣體有O_2、N_2、NO、CO和CO_2;在Rh7團(tuán)簇A結(jié)構(gòu)上發(fā)生物理吸附的氣體有O_2、N_2、CO、CO_2、NO;在Rh7團(tuán)簇B結(jié)構(gòu)上發(fā)生物理吸附的氣體有H_2、O_2、N_2、CO、CO_2、NO、NO_2。這八種氣體在三個(gè)結(jié)構(gòu)上均能發(fā)生化學(xué)反應(yīng)的是N_2O。就發(fā)生物理吸附的氣體而言,Ead(NO)Ead(O_2)≈Ead(NO_2)≈Ead(CO)Ead(N_2)≈Ead(CO_2)Ead(H_2)。在與八種氣體的相互作用中,存在電荷轉(zhuǎn)移。電荷轉(zhuǎn)移的多少,與氣體分子中是否含有O元素相關(guān),氣體中存在O元素,則能得到更多的電子。就發(fā)生物理吸附的氣體而言,電荷轉(zhuǎn)移情況:q(CO_2)≈q(O_2)q(NO_2)q(NO)≈q(CO)q(N_2)q(H_2)。
[Abstract]:Based on the isothermal molecular dynamics and first-principles density functional theory (Density Functional Theoryn DFT), the annealing behavior of Au-PdU Au-Ag and Au-Pt bimetallic clusters with different sizes and different sizes are calculated as follows: Au-PdU Au-Ag and Au-Pt bimetallic clusters. The geometric structure and electronic properties of the mixed metal cluster (AuSch 12Pt and PtSZ 12Au.) the ground state structure characteristics of the mixed metal cluster, And the ground state structure and electronic properties of the adsorbed small molecule S / H _ 2O _ 2N _ T _ 2N _ T _ 2NOT _ 2N _ 2C _ 2C _ 2T _ 2C _ 2C _ 2C _ 2T _ 2C _ 2C _ 2C _ 2C _ 2C _ 2T _ 2O _ 2N _ 2C _ 2C _ 2N _ 2O _ The main conclusions are as follows: (1) the au atoms of bimetallic Au-Pd and Au-Pt clusters tend to segregate when annealing occurs: the au atoms tend to occupy the surface when the specific gravity of au atoms is less than PD or Pt atoms; When the specific gravity of the two atoms is close, the au atoms occupy most of the surface of the cluster. The segregation of Ag atoms occurs in bimetallic Au-Ag clusters, and the segregation behavior is similar to that of au atoms in Au-PdO Au-Pt) clusters. In Au-Pt bimetallic clusters, with the increase of au atom specific gravity, the 未 -CV curve will change from disorder to order.) based on the first-principle DFT, the geometric structure and electronic properties of pure metal clusters (AuStuc 13) and PTS (13) and mixed metal clusters (Austi 12Pt and PTV 12Au2) have been calculated. The results show that a new ground state candidate has been found. The pure metal clusters of 13 atoms have obvious low energy isomerism (especially AuStue 13) clusters, but the homogeneity phenomenon of the original clusters can be restrained by doping the Autopt13 elements. In the calculation of Vertical Ionization potential VIPs and Vertical Electron affinities (VEAA), it is found that the VIP and VEA values of these clusters are similar to those of the experimental ones (where relativistic is present, the influence of doping on VIP and VEA is relatively small. But doping can change the distribution of d electrons at the Fermi energy of clusters. The distribution of d electrons at Fermi energy in the cluster may be related to its catalytic activity. (3) the ground state structure and electronic structure characteristics of the main structure and electronic structure of the Rh / S / S / C / S / S / C / S / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C / C clusters are studied, and the ground state structure and electronic structure characteristics of the clusters are studied by first-principle DFT calculations than by using the first principle DFT method. The results show that the symmetry of the ground state structure of the 1: Rh6 cluster is Oh and there is no competitive ground state structure of the low energy isomer Rh7 cluster. The gas of physical adsorption on Rh6 cluster is O _ 2O _ 2S _ 2NOCO and CO _ 2s _ 2; the gas of physical adsorption on Rh7 cluster A is O _ 2N _ 2C _ 2C _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2no _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O _ 2O It is N _ 2O _ 2 that can react on all three structures of these eight gases. As far as the gas for physical adsorption is concerned, Eadnou No2) 鈮，

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