DFT Study of Thiophene Adsorption on the Pd（111） and Pt（111） Surfaces

Thiophene adsorption on the(111) surfaces of Pd and Pt have been investigated by density functional theory.The results indicate that the adsorption at the hollow sites is the most stable.To our interest,the molecular plane of thiophene ring is distorted with C=C bond being elongated to 1.450  and C-C bond being shortened to 1.347 ,and the C-H bonds tilt 13.91～44.05o away from this plane.Furthermore,analysis on population and density of states verified the calculated adsorption geometries.Finally,charge analysis suggests that thiophene molecule is an electron acceptor,reflecting the interaction between the lone pair of sulfur and the d-orbitals of metal.     

Pt（111）和Pt3Ni（111）表面上CO催化氧化反应的密度泛函理论研究

采用密度泛函理论,对Pt(111)和Pt3Ni(111)表面上CO和O的单独吸附、共吸附以及CO的氧化反应进行了系统的研究. 结果表明, Pt3Ni(111)表面上CO的吸附弱于Pt(111)表面, O的吸附明显强于Pt(111)表面. 两个表面表现出相似的CO催化氧化活性. 表面Ni的存在不但稳定了O的吸附,同时也降低了过渡态O的能量.     

Comparative Study of Hypophosphite H2PO2^- Adsorption on Ni（111） and Ag（111） Surfaces by DFT

Surface structures and electronic properties of hypophosphite H2PO2^- on Ni（111） and Ag（111） surfaces were investigated by means of density functional theory at B3LYP/6-31 ＋ ＋G（d,p） level. The most stable structure was that in which the H2PO2^- adsorbs with its two P--O bonds faced to the substrate surface. The results of the Mulliken population analysis showed that because of the subtle difference of electron configuration, the adsorption energy was larger on the Ni surface than on the Ag surface, and the amounts of both donation and back donation were larger on the Ni（111） surface than on the Ag（111） surface. There were more negative Mulliken charge transfer from H2PO2^- to substrate clusters on Ni surface than on Ag surface and more positive Mulliken charges on P atom in Ni4H2PO2^- than in Ag4H2PO2^-, which means that P atom in Ni4H2PO2^- is easily attacked by a nucleophile such as OH . Thus, H2PO2^- is more easily oxidated on Ni（111） surface than on Ag（111） suface. These results indicated that the silver surface is inactive for the oxidation reaction of the hypophosphite anion.     

Interaction of Hg Atom with Bare Si（111） Surface

1INTRODUCTION In the past decades,mercury has been a very use-ful electrode material in the fabrication and electrical measurement of molecule modified metal-metal and metal-semiconductor junctions.Majda et al.[1,2]constructed a symmetric Hg-SCn-CnS-Hg junction to study the electron tunneling properties of alkanethio-late bilayers.Whitesides et al.[3～5]fabricated Hg-SAM/SAM-Metal(Ag,Au,Cu)junctions to investi-gate the electrical breakdown voltage of self-assem-bled monolayers(SAMs…     

氧化锌有序结构在Au(111)和Cu(111)上的生长（英文）

利用NO_2或O_2作为氧化剂,研究了氧化锌在Au(111)和Cu(111)上的生长和结构。NO_2表现了更好的氧化性能,有利于有序氧化锌纳米结构或薄膜的生长。在Au(111)和Cu(111)这两个表面上,化学计量比氧化锌都形成非极性的平面化ZnO(0001)的表面结构。在Au(111)上,NO_2气氛下室温沉积锌倾向于形成双层氧化锌纳米结构;而在更高的沉积温度下,在NO_2气氛中沉积锌则可同时观测到单层和双层氧化锌纳米结构。O_2作为氧化剂时可导致形成亚化学计量比的ZnOx结构。由于铜和锌之间的强相互作用会促进锌的体相扩散,并且铜表面可以被氧化形成表面氧化物,整层氧化锌在Cu(111)上的生长相当困难。我们通过使用NO_2作为氧化剂解决了这个问题,生长出了覆盖Cu(111)表面的满层有序氧化锌薄膜。这些有序氧化锌薄膜表面显示出莫尔条纹,表明存在一个ZnO和Cu(111)之间的莫尔超晶格。实验上观察到的超晶格结构与最近理论计算提出的Cu(111)上的氧化锌薄膜结构相符,具有最小应力。我们的研究表明,氧化锌薄膜的表界面结构可能会随氧化程度或氧化剂的不同而变化,而Cu(111)的表面氧化也可能影响氧化锌的生长。当Cu(111)表面被预氧化成铜表面氧化物时,ZnOx的生长模式会发生变化,锌原子会受到铜氧化物晶格的限域形成单位点锌。我们的研究表明了氧化锌的生长需要抑制锌向金属基底的扩散,并阻止亚化学计量比ZnOx的形成。因此,使用原子氧源有利于在Au(111)和Cu(111)表面上生长有序氧化锌薄膜。     

Topography Structure and Scanning Tunneling Spectrum of Nickel（Ⅱ）-tetraphenylporphyrin Molecules on Au（111）

1 INTRODUCTION Metalloporphyrins are intensively studied for many reasons. They have been comprehensively used in biochemistry, analytical chemistry and so on. They play an important role in biological processes such as oxygen transport photosynthesis and enzyme catalysis. They can act as catalysts[1], and can undergo reversible redox reactions in which the site of electron transfer may be localized on the por- phyrin ring or on the central metal ion. Both reaction types are important in…     

Au(111)表面Verdazyl自由基的构象转换（英文）

本文使用扫描隧道显微镜(STM)与密度泛函理论(DFT)技术,研究了1,5-二异丙基-3-(苯并[b]苯并[4,5]噻吩并[2,3-d]噻吩-2-基)-6-oxoverdazyl分子(简称B2P分子)与1,5-二异丙基-3-(苯并[b]苯并[4,5]噻吩并[2,3-d]噻吩-4-基)-6-oxoverdazyl分子(简称B4P分子)在Au(111)表面的吸附与构象转换行为。B2P分子在Au(111)表面可形成单体、二聚体、三聚体与四聚体结构,无法形成有序组装结构,且在STM图像上可观测到"P"构象与"T"构象两种构象。而对于B4P分子,当覆盖度较低时在Au(111)表面形成二聚体结构,覆盖度较高时则形成有序的组装结构,同样的,B4P分子在STM图像上也可以观测到"P"构象与"T"构象。在+2.0 V的偏压下,B2P与B4P都可以通过针尖诱导发生构象转换。结合STM图像与DFT模拟结果,确认了两种构象的差异源于分子的verdazyl自由基与Au(111)表面的夹角不同。     

Pt（111）表面上一氧化碳的吸附与氧化反应

Ｐｔ（１１１）表面上一氧化碳的吸附与氧化反应１）刘金尧（清华大学一碳化工国家重点实验室北京１０００８４）ＸｕＭＺａｅｒａＦ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙＵｎｉｖｅｒｓｉｔｙｏｆＣａｌｉｆｏｒｎｉａＲｉｖｅｒｓｉｄｅＣＡ９２５２１）关键词...     

（100），（110）和（111）生长方向的La0.7Sr0.3MnO3薄膜结构及性能研究

利用磁控溅射方法，在（100），（110）和（111）LaAlO3（LAO）衬底上制备得到了不同生长方向的La0.7Sr0.3MnO3（LSMO）薄膜并对其晶体结构及磁电学性能进行了系统研究。AFM图揭示出（100），（110）和（111）生长方向的LSMO薄膜分别具有圆形、长条形和点状的表面晶粒形貌。磁电学测试结果表明不同生长方向的LSMO薄膜磁电学性能与其应变程度有关。（111）生长方向的LSMO薄膜由于按最密排面生长，晶格畸变很小，从而具有相对最大的磁饱和强度值和最低的电阻。     

n—GaAs（100）,Si（111）表面修饰卟啉分子的光致界面电荷转移…

利用表面光电压谱研究了四碘化四－（４－三甲胺苯基）卟啉（ＴＴＭＡＰＰＩＨ２）修饰ｎ－ＧａＡＳ（１００）和ｎ－Ｓｉ（１１１）半导体表面的光致界面电荷转移特性。结果表明，ｎ－ＧａＡｓ（１００）表面修饰ＴＴＭＡＰＰＩＨ２分子的光致界面电荷转移效率远比ｎ－Ｓｉ（１１１）表面修饰的高，并且发现在该卟啉分子的非吸收区也有明显的光致界面电荷转移现象，而与ｎ－Ｓｉ（１１１）间则没有这种转移特性。用电化学测量和ＵＶ     

A DFT Study of Thiophene Adsorption on the Rh（111） Surfaces

Thiophene adsorption on the Rh(111) surfaces has been investigated by density functional theory.The results show that the adsorption at the hollow and bridge sites is the most stable.The molecular plane of the thiophene ring is distorted,the C=C bond is stretched to 1.448  and the C-C bond is shortened to 1.390.The C-H bonds tilt 22～42oaway from the surface.The calculated adsorption geometries are in reasonable agreement with population analysis and density of states.The thiophene molecule obtains 0.74 electrons,reflecting the interaction between the lone pair of sulfur and the d-orbitals of metal.The reaction paths and transition states for desulfurization of the molecule have been investigated.The bridge adsorption structure of thiophene leads to a thiol via an activated reaction with an energetic barrier of 0.30 eV.This second step is slightly difficult,and dissociation into a C4H4 fragment and a sulfur atom is possible,with an energetic barrier of 0.40 eV.     

金刚石（111）清洁／附氢表面与甲基的相互作用

利用Ａｍｌ分子轨道法计算了金刚石（１１１）清洁／附氢表面与甲基相互作用的特殊势能曲线，深入研究了清洁、附氢表面与甲基相互作用下基底弛豫重建、四甲基构型及成键能的差别，进而得到附氢表面较清洁表面更适合于甲基吸附，是更好的金刚石薄膜生长址的结论。在距基底表面０．５ｎｍ内，甲基与清洁、附氢表面皆有强烈的相互作用。     

苯在CuCl（111）表面吸附的密度泛函理论研究

采用量子化学的密度泛函理论方法,探讨了苯分子在CuCl(111)表面上不同覆盖度下不同吸附位上的平行吸附行为. 计算结果表明,随覆盖度的减小,吸附作用增强, Cl位上的吸附是稳定的吸附模式,在低覆盖度下吸附能约为74 kJ/mol, 在顶位和穴位上的吸附属于较弱的物理吸附. 同时对吸附前后的电子布居和态密度进行了分析. 吸附过程中,苯分子的π电子向底物转移,同时Cu的 3d轨道的电子反馈给苯的反键π轨道.     

HDEHP－正庚烷溶剂萃取法从大量Ag（Ⅰ），Cu（Ⅱ）存在的硝酸溶液中分离In（Ⅲ）或￣（111）In（Ⅲ）

ＨＤＥＨＰ－正庚烷溶剂萃取法从大量Ａｇ（Ⅰ），Ｃｕ（Ⅱ）存在的硝酸溶液中分离Ｉｎ（Ⅲ）或￣（１１１）Ｉｎ（Ⅲ）周德海（四川大学原子核科学技术研究所，成都６１００６４）￣（１１１）Ｉｎ是国际上公认的最重要的医用核素之一。它用于脑脊髓瘤显像￣［１］、恶性...     

Density Functional Theory Study of Water Diffusion and Clustering on Pd（111）

1 INTRODUCTION The interaction of water molecules with metal sur- faces plays a vital role in a number of important pro- cesses, such as corrosion, heterogeneous catalysis, electrochemical processes in aqueous solutions, hydrogen production, etc.[1] The structure and pro- perties of water adsorbed on well-defined metal sur- faces have been the subject of numerous experi- mental and theoretical investigations. There have been a number of experimental studies of water on metal surfaces throu…     

Growth Kinetics of Silicon Carbide Film Prepared by Heating Polystyrene/Si（111）

SiC films were prepared by heating polystyrene/Si（111） in normal pressure argon atmosphere at different temperatures. The films were investigated by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared absorption measurements. The thicknesses of SiC films were calculated from FTIR spectra. The growth kinetics of the growth process of SiC films were investigated as well. The thicknesses of the SiC films grown for 1 h with increasing growth temperatures have different trends in the three temperature ranges： increasing slowly （1200-1250 ℃）, increasing quickly （1250- 12.70 ℃）, and decreasing （1270-1300 ℃）. The apparent activation energies of the growth process of SiC films in the three ranges were calculated to be 122.5,522.5, and -127.5 J/mol respectively. Mechanisms of the different growth processes were discussed. The relation between film thicknesses and growth temperatures indicated that the growth process was a 2D mechanism in the first range and 3D mechanism in the second range. In the third range, the thicknesses of SiC films were decreased by the volatility of Si and C atoms.     

过渡金属替代的CeO2（111）表面上NO+CO反应机理的理论研究（英文）

采用DFT+U方法研究了过渡金属替代的CeO2(111)表面上的NO+CO反应机理,以探求不同过渡金属对N2选择性的影响.结果表明,在反应过程中,反应活性中心由过渡金属单原子与其最近邻的氧空位组成.NO在过渡金属-氧空位上发生N–O断键,不同过渡金属上该还原步骤的难易程度不同.计算发现,右过渡金属Rh,Pd和Pt替代的CeO2(111)表面可以与吸附物之间形成较强的吸附作用,进而可以达到较高的N2选择性.其主要原因是右过渡金属具有较多的d电子,可以与吸附小分子之间形成有效的反馈键.而左过渡金属拥有较少的d电子,难以有效抓住吸附物,最终导致较低的N2选择性.     

A Periodic Density Functional Study on Adsorption Properties of Methoxy on Au（111） Surface

1INTRODUCTION Methoxy(CH3O)has been identified as the first intermediate in the decomposition of methanol on extensive list of clean transition metal surfaces,such as Ni(100)[1],Cu(100)[2,3],Cu(111)[4],Ag(111)[5],Au(110)[6],Pd(111)[7]and Ru(0001)[8].The electronic structure of the metal is a determining factor in OH bond scission.In fact,group IB clean surfaces have shown very low activity towards this reaction,al-though there are reports on low amounts of methoxy formed on clean Cu(…