第一性原理研究O_2和H_2O 在ZnO ■表面上的吸附行为

运用基于密度泛函理论(DFT)的第一性原理方法研究了O_2和H_2O单分子在ZnO■表面上的吸附行为.吸附位点主要考虑了表面的Zn顶位和Zn桥位,同时也考虑了其它可能的吸附行为.对于O_2在ZnO■表面上的吸附设计了9个模型,H_2O在ZnO■表面上的吸附设计了12个模型.通过形成能计算发现,O_2在表面上的吸附为正值,H_2O的吸附为负值.O_2和H_2O单分子在表面上发生分子吸附,未见解离形态.对于O_2吸附最稳定的结构是O_2分子与表面相邻的Zn原子形成了Zn_(slab1)-O_(ads1)-O_(ads2)-Zn_(slab2)桥连键.其它较为稳定的结构是O_(ads1)原子迁移到下一个表面重复晶胞的O原子位置附近,在表面上形成了Zn_(slab1)-O_(ads1)键,同时O_(ads2)原子扩散至表面沟渠上方.对于H_2O吸附,不论以何种方式吸附结构都比较稳定.其中最稳定的构型是O_(ads)迁移到下一个表面重复晶胞的O原子位置附近,形成了Zn_(slab1)-O_(ads)键以及O_(slab3)-H氢键.另外较稳定的构型是O_(ads)迁移到ZnO■表面台阶上方,形成了Zn_(slab1)-O_(ads)键以及O_(slab1)-H氢键.     

AlM(M=O,S,Se,Te,Po)势能函数和光谱研究

本文用B3LYP方法,相对论有效实势,其中铝原子用6-311 G(d,p)基组,其它用sddall基组分别对AlM(M=O,S,Se,Te,Po)分子进行了优化计算,得出了它们的平衡结构和双原子分子光谱常数.计算结果表明:它们的基态结构分别为AlO(2Σ),AlS(2Σ),AlSe(2Σ),AlPo(2Σ),其中AlO和AlS的计算数据与实验结果是一致的.氧簇元素原子与铝结合的中性双原子分子的平衡距离,随原子序数的增加而增长,离解能随原子序数的增加而减小,但它们都能形成稳定的双原子中性分子.它们的谐振频率随原子序数的增加而减小,它们的最低空轨道和最高占据轨道能量随原子序数的增加而略有增加,但变化不大.其能隙随原子序数的增加而略有增加.本文从理论上系统地研究了氧簇元素的原子(包括放射性较强,不太稳定的Po)与铝原子形成的中性双原子分子的光谱和分析势能函数.     

钚氧化物的分子结构和分子光谱研究

用杂化密度泛函(B3LYP)方法,Pu原子采用相对论有效原子实势(RECP),O原子采用全电子6-311g(d)基组优化了PuO,PuO2,Pu2O3的分子结构,得到了相应的平衡几何构型,并计算了红外振动频率(IR)、Raman光谱.结果表明:PuO,PuO2分子基态几何构型和振动频率与实验值相符.对Pu2O3分子可能的构型和多重性进行结构优化,发现Pu2O3分子基态为11B2的C2v构型,给出了Pu2O3分子基态结构的红外和拉曼光谱数据、力常数等系列数据,并对振动频率的峰值进行了指认.通过自然键轨道(NBO)分析,发现由钚到氧的电荷转移.相对于PuO和PuO2分子,在Pu2O3中形成较弱的Pu—O键.分析自旋布居,发现在这些分子中,自旋磁动量大都由Pu原子的5f电子贡献,而氧原子的2p轨道往往贡献反平行的自旋.     

BaxOy小团簇修饰Ru(0001)表面的结构稳定性和氮分子吸附性质

为了说明钡助剂的存在形式, 本文采用第一性原理方法研究了Ba_xO_y小团簇修饰Ru(0001)表面的结构稳定性和氮分子吸附性质. 基于总能的热力学分析发现, 在实验条件下(500 K, P_H2O/P_H2<10^-3), Ba₂O团簇比BaO₂, BaO, Ba和O等团簇(原子)更加稳定. 这证实含有金属性钡原子的团簇也是氧化钡助剂可能的工作状态. 表面电荷差分密度说明Ba₂O团簇的氧和钡原子与衬底的作用不同. 不过Ba₂O团簇氧和钡原子附近的氮分子吸附行为相似, Ba₂O团簇增强了氮分子和衬底的相互作用. Ba₂O团簇氧和钡原子附近的氮分子吸附能分别为0.78 和0.88 eV, 均大于清洁表面的0.67 eV. 氮分子间距和氮分子的拉伸振动频率都表明Ba₂O团簇在一定程度上活化了吸附氮分子. Ba₂O团簇氧和钡原子附近的N–N键长分别为0.117和0.116 nm, 大于清洁表面的0.114 nm. 氧和钡原子附近氮分子的拉伸振动频率分别为 1888 和1985 cm^-1, 小于清洁表面的2193 cm^-1. 电荷差分密度的计算结果说明, 削弱作用主要来自于Ba₂O团簇中钡离子和氮分子间的静电作用. 两者间的静电作用增加了氮分子π 反键轨道的占据数, 促进了氮分子极化, 从而削弱氮分子键.     

第一性原理研究O2和H2O在ZnO (101 ̅0)表面上的吸附行为

运用基于密度泛函理论(DFT)的第一性原理方法研究了O2和H2O单分子在ZnO (101 ̅0)表面上的吸附行为。吸附位点主要考虑了表面的Zn顶位和Zn桥位，同时也考虑了其它可能的吸附行为。对于O2在ZnO (101 ̅0)表面上的吸附设计了9个模型，H2O在ZnO (101 ̅0)表面上的吸附设计了12个模型。通过形成能计算发现，O2在表面上的吸附为正值，H2O的吸附为负值。O2和H2O单分子在表面上发生分子吸附，未见解离形态。对于O2吸附最稳定的结构是O2分子与表面相邻的Zn原子形成了Znslab1-Oads1-Oads2-Znslab2桥连键。其它较为稳定的结构是Oads1原子迁移到下一个表面重复晶胞的O原子位置附近，在表面上形成了Znslab1-Oads1键，同时Oads2原子扩散至表面沟渠上方。对于H2O吸附，不论以何种方式吸附结构都比较稳定。其中最稳定的构型是Oads迁移到下一个表面重复晶胞的O原子位置附近，形成了Znslab1-Oads键以及Oslab3-H氢键。另外较稳定的构型是Oads迁移到ZnO (101 ̅0)表面台阶上方，形成了Znslab1-Oads键以及Oslab1-H氢键。     

NO在清洁和Cs覆盖的Ru(100)表面上吸附的热脱附谱

用热脱附谱等方法研究了NO分别在清洁和Cs覆盖的Ru(1010)表面上的吸附.结果表明:存在两种NO分子吸附态(a1,a2),脱附温度分别处于325℃和550℃附近.Cs的存在增加了Ru(1010)表面上a2态的吸附位置,提高了该态的脱附温度.Cs在Ru(1010)表面上的存在同时促进了吸附NO分子的分解.NO在Ru(1010)表面上分解后形成吸附O原子和N原子.N原子复合以N2在约500℃附近脱附,同时Cs的存在也促进了N2O的形成.在Cs覆盖的Ru(1010)表面上,N2O的脱附温度约在425℃.     

NO Case(b)情况下的非弹性散射及Λ相关量子干涉的理解（英文）

在理论研究中,对洪德情况(a)下2Π态原子-双原子分子碰撞诱导转动传能中的量子干涉已经进行了研究.为了对Λ相关的原子-双原子分子碰撞系统进行更进一步的研究,建立了洪德情况(b)下原子-双原子分子动力学模型.讨论洪德情况(b)下双原子分子的干涉程度,对NO洪德情况(b)下与He、Ne、Ar碰撞的干涉角进行了定量计算.在含时一级波恩近似下,考虑各向异性相互作用势,讨论各个因素(实验温度、碰撞伴、转动量子数等)对干涉角的影响.     

第一性原理分析CO_2在CaO(100)表面的吸附性能

运用广义梯度密度泛函理论(GGA-PW91)结合周期平板模型方法,研究了CO_2分子分别在1×1×1和2×2×1CaO(100)超晶胞面最稳定位的吸附行为.结果表明:Ca O(100)表面的Osurf原子为CO_2分子的有效吸附位,能够和CO_2分子形成稳定吸附键C-Osurf,其吸附能为0.858 e V.在吸附前后C和Osurf原子的价电子组态分别由2s~(0.89)2p~(2.47)和2s~(1.84)2p~(4.99)变化为2s~(0.68)2p~(2.33)和2s~(1.90)2p~(5.17),而且在CO_2分子中的O2s原子与Surface层的Ca_(sub)4s原子间存在相互作用.考察了多个CO_2分子在2×2×1 Ca O(100)表面吸附时存在分子间相互排斥作用,发现当四个CO_2分子吸附到2×2×1CaO(100)超晶胞面时,排斥能为1.76e V,不利于CO_2分子的吸附.     

Ru(0001) 表面BaO吸附层的原子结构和氮分子的吸附性质

采用密度泛函理论研究了Ru(0001) /BaO表面的原子层结构和氮分子的吸附性质. 研究结果表明, 在低覆盖度下氧化钡倾向于以相同的构型形成Ru(0001) 表面原子层. 在此构型中, 氧原子位于表面p(1× 1) 结构的hcp谷位, 而钡原子则位于同一p(1× 1) 结构的顶位附近. 钌氧键键长等于0.209 nm, 比EXAFS的实验值大0.018 nm. 在Ru(0001) /BaO表面氮分子倾向吸附于钡原子附近. 相应位置的氮分子吸附能位于0.70到0.87 eV之间, 大于氧原子附近的氮分子吸附能. 钡原子附近的钌原子对氮分子具有更强的活化性能. 相应位置的氮分子拉伸振动频率等于1946 cm^{- 1}, 比氧原子附近的最大分子振动频率小约130 cm^-1. Ru(0001) /BaO表面氮分子键强度介于清洁Ru(0001) 和Ru(0001) /Ba表面之间. Ru(0001)/BaO表面不同位置的氮分子吸附性质差异是由钡和氧原子化学性质不同造成的. 表面钡原子的作用能够减少吸附氮分子的σ^*轨道电子密度, 增加π^*轨道电子密度, 从而增强氮分子和钌原子间的轨道杂化作用, 弱化氮分子键.     

部分气体双原子分子的完全振动能谱和离解能的精确研究

鉴于气体双原子分子H2、O2、N2和CO的高振动激发态能级和离解行为在实际研究中的重要性,本文应用代数方法(AM)和代数能量方法(AEM),以部分气体双原子分子有限的实验能级[Ev]为基础,获得了H2-X1∑ g、O2-A3∑ u、O2-c1∑-u、N2-X1∑ g和CO-X1∑ 共5个电子态的完全振动能谱{Ev}及其分子的离解能,为研究部分离解气体的物理和化学性质提供了重要的高振动激发态能级和可靠的离解能数据.     

Structural and Interaction Properties of Porphyrin Layers — A Quantum Chemical Study

This paper is proposed to understand the interaction of porphyrin layers with diatomic molecules interacting at their interior regions by applying ab initio and density functional theory(DFT) methods. We have used NO, CO, and O2 diatomic molecules to interact with the porphyrin layers. The most common Fe-centered metalloporphyrin structure with tetra-pyrrlic rings having N4 core is chosen for the study. The optimization of Porphyrin-Porphyrin(P I-P II)and Porphyrin-Diatomic molecule-Porphyrin(P I-AB-P II)(AB = NO, CO, and O2) complexes are performed using HF method. In order to understand the planarity and appropriate stacking size of porphyrins and also to infer the separation of diatomic molecules between porphyrin layers the behavior of P I-AB-P II complexes(where AB = NO, CO, and O2)are analyzed using structural properties and molecular electrostatic potentials(MEP). The MEPs are calculated using hybrid exchange correlation functional B3PW91 of DFT along with 6-31+G* basis set for the P I-P II and P I-AB-P II complexes obtained from HF method.     

Shock compression of deuterium near 100 GPa pressures

The shock-compression curve (Hugoniot) of D2 near 100 GPa pressures (1 Mbar) has been contro-versial because the two published measurements have limiting compressions of fourfold and sixfold. Our purpose is to examine published experimental results to decide which, if either, is probably correct. The published Hugoniot data of low-Z diatomic molecules have a universal behavior. The deuterium data of Knudson et al. (fourfold limiting compression) have this universal behavior, which suggests that Knudson et al. are correct and shows that deuterium behaves as other low-Z elements at high tem-peratures. In D2, H2, N2, CO, and O2, dissociation completes and average kinetic energy dominates average potential energy above approximately 60 GPa. Below approximately 30 GPa, D2, H2, N2, CO, and O2 are diatomic. D2 dissociation is accompanied by a temperature-driven nonmetal-metal transition at approximately 50 GPa.     

FeP(Im)-AB Bonding Energies Evaluated with A Large Number of Density Functionals (P = porphine, Im = imidazole, AB = CO, NO, and O(2))

Sixty-four (64) density functionals, ranging from GGA, meta-GGA, hybrid GGA to hybrid meta-GGA, were tested to evaluate the FeP(Im)-AB bonding energies (E(bond)) in the heme model complexes FeP(Im)(AB) (P = porphine, Im = imidazole, AB = CO, NO, and O(2)). The results indicate that an accurate prediction of E(bond) for the various ligands to heme is difficult with the DFT methods; usually a functional successful for one system does not perform equally well for the other system(s). Relatively satisfactory results for the various FeP(Im)-AB bonding energies are obtained with the meta-GGA funtionals BLAP3 and Bmτ1; they yield E(bond) values of ca.1.1, 1.2, and 0.4 eV for AB = CO, NO, and O(2), respectively, which are in reasonable agreement with experimental data (0.78 - 0.85 eV for CO, 0.99 eV for NO, and 0.44 - 0.53 eV for O(2)). The other functionals show more or less deficiency for one or two of the systems. The performances of the various functionals in describing the spin-state energetics of the five-coordinate FeP(Im) complex were also examined.     

X-ray emission spectra of small molecules

An instrument for X-ray emission studies of free molecules is described and electron and fluorescence excitations are discussed. The application of X-ray emission spectroscopy to free molecules is exemplified by the spectra of N₂, CO, NO and CO₂. From the spectra the core level binding energies of the molecules are deduced. For the diatomic molecules vibrational fine structure is resolved and analyzed in terms of different bond lengths in the initial and final states. The change in bond length, when the initial 1s vacancy is formed, is also discussed. The influence of the X-ray selection rules and molecular localization properties on the band intensities are discussed and exemplified by the O1s and C1s spectra of CO and CO₂. In the spectra about ten satellites are found.     

高温下黑索金（RDX）热分解动力学模拟

应用分子动力学模拟方法研究了黑索金(RDX)在纯高温下的分解机理, 研究结果表明RDX初始分解机理主要为N-N键的断裂形成NO2分子, 然后发生H原子转移反应形成H2O, HONO, HO和NO分子; 通过对RDX热分解反应物和生成物的研究结果表明N2和H2O分子是RDX分解过程中最稳定的生成物, NO2, HNO3, NO, NO3和HONO分子为RDX热分解过程中的中间产物; 在高温4500K, CO, CO2和OH分子出现的频率逐渐提高, 表明这几种分子在高温下更容易形成.     

高温下黑索金（RDX）热分解动力学模拟

应用分子动力学模拟方法研究了黑索金(RDX)在纯高温下的分解机理, 研究结果表明RDX初始分解机理主要为N-N键的断裂形成NO2分子, 然后发生H原子转移反应形成H2O, HONO, HO和NO分子; 通过对RDX热分解反应物和生成物的研究结果表明N2和H2O分子是RDX分解过程中最稳定的生成物, NO2, HNO3, NO, NO3和HONO分子为RDX热分解过程中的中间产物; 在高温4500K, CO, CO2和OH分子出现的频率逐渐提高, 表明这几种分子在高温下更容易形成.     

Sub‐picosecond Raman spectrometer for time‐resolved studies of structural dynamics in heme proteins

We describe a pump–probe Raman spectrometer based on a femtosecond Ti:sapphire laser, an optical parametric generator and two optical parametric amplifiers for time‐resolved studies, with emphasis on the structural dynamics in heme proteins. The system provides a 100‐fs pump pulse tunable in the range 500–600 nm and a transform‐limited sub‐picosecond probe pulse tunable in the range 390–450 nm. The spectrometer has spectral (25 cm⁻¹) and temporal (∼0.7 ps) resolutions which constitute an effective compromise for identifying transient heme protein species and for following their structural evolution by spontaneous Raman scattering in the time range 0.5 ps to 2 ns. This apparatus was applied to time‐resolved studies of a broad range of heme proteins, monitoring the primary dynamics of photoinduced heme coordination state and structural changes, its interaction with protein side‐chains and diatomic gaseous ligands, as well as heme vibrational cooling. The treatment of transient Raman spectra is described in detail, and the advantages and shortcomings of spontaneous resonance Raman spectroscopy for ultrafast heme proteins studies are discussed. We demonstrate the efficiency of the constructed spectrometer by measuring Raman spectra in the sub‐picosecond and picosecond time ranges for the oxygen‐storage heme protein myoglobin and for the oxygen‐sensor heme protein FixLH in interaction with the diatomic gaseous ligands CO, NO, and O₂. Copyright © 2010 John Wiley & Sons, Ltd.     

Adsorption and interaction of CO and NO on Pt(410): I. TPD studies

NO and CO adsorption and the NO/CO reaction on Pt(410) are studied by TPD. NO is found to dissociate on Pt(410) at 120 K, but it reacts to form N₂O at higher exposures. The N₂O desorbs in two peaks at 135 and 150 K. CO adsorbs molecularly, and desorbs in 5 peaks at 550, 500, 450, 380 and about 130 K. CO is also found to dissociate upon heating, leaving a carbon residue on the surface which changes the TPD spectra. The NO/CO reaction shows a surface explosion at 360 K. These results provide additional evidence that Pt(410) has unusual reactivity, as predicted by Banholzer, Park, Mak and Masel, Surface Sci. 128 (1983) 176.     

气体分子在Co-BN表面吸附的第一性原理研究

采用包含色散力校正的密度泛函理论(DFT-D)方法系统地研究了气体分子(O2, H2, NO, CO, CO2, SO2, H2S, H2O)在Co掺杂单层BN(Co-BN)表面的吸附, 分析了吸附小分子的几何结构, 吸附能, 电荷转移等情况. 结果表明: 1) CO等气体分子主要吸附在Co及其近邻六元环的顶位, 吸附结构的电荷转移表明掺杂原子Co对BN衬底的气敏特性有较好的调制作用; 2) 在Co-BN表面吸附的O2和CO较易被活化, 表明Co-BN可能是一种对CO氧化有较好催化活性的新型催化材料.     

Adsorption and valence electronic states of nitric oxide on metal surfaces

Among fundamental diatomic molecules, the adsorption of carbon monoxide (CO) and nitric oxide (NO) on metal surfaces has been a subject of intensive research in the surface science community, partly owing to its relevance to heterogeneous catalysis used for environmental control. Compared to the rather well-defined adsorption mechanism of CO, that of NO is less understood because the adsorption results in much more complex reactions. The complexity is ascribed to the open-shell structure of valence electrons, making the molecule readily interact with the metal surface itself as well as with co-adsorbed molecules. Furthermore, the interaction crucially depends on the local structure of the surface. Therefore, to elucidate the interaction at the molecular scale, it is essential to study the valence state as well as the bonding geometry for individual NO molecules placed in a well-defined environment on the surface. Scanning tunneling microscopy (STM) is suitable for this purpose. In this review, we summarize the knowledge about the interaction of NO with metal surfaces, mainly focused on the valence electronic states, followed by recent studies using STM and atomic force microscopy (AFM) at the level of individual molecules.