电子振动近似理论和氢同位素在金属钛中的溶解度(三)

本文论述了电子-振动近似理论,并应用于TiH2、TiD2和TiT2基态3A2的计算,即用单个分子TiH2、TiD2和TiT2中的电子和振动能量和熵近似代表他们处于固态时的能量和熵,所得到的金属钛的氢化热力学函数ΔH0、ΔS0、ΔG0以及平衡压力与温度的关系,与文献符合很好.这表明电子振动近似理论的可应用性.计算方法为密度泛函理论B3P86/6-311G**.在此基础上进一步计算氢同位素在金属钛中的溶解度,结果合理.     

氢同位素化合物TiH2，TiD2和TiT2的电子

根据原子分子反应静力学和群论，确定TiH2，TiD2和TjT2的基电子状态为^3A2．应用基函数6-311G^＊＊和密度泛函理论B3P86方法，全电子计算了氢同位素分子及其钛化物的能量E、定容热容Cv和熵S应用电子振动近似理论，即用单个分子TiH2，TiD2和TjT2中的电子和振动能量和熵近似代表他们处于固态时的能量和熵,计算所得到的金属钛的氢化热力学函数△Hc^0，△S^0，△G^0以及平衡压力与温度的关系，与文献符合很好，这表明电子振动近似理论的可应用性，选用金属钛作为中子靶是很正确的。     

CoH生成热力学函数的量子力学计算

用B3LYP/SDD密度泛函方法计算了CoH的微观性质、CoH(g)、CoD(g)和CoT(g)的能量 (E)和熵(S) ,进而计算Co与H2 、D2 、T2 反应的ΔH 、ΔG 、ΔS .CoH分子的基电子状态为三重态 ,Re、D 0 、ωe 分别为 1.5 2nm、2 77.84kJ/mol和 132 1cm-1,与实验值基本一致 .在固态分子的E和S的计算中 ,以气态分子计算得到的总能量中的振动能Ev 代替固态能量 ,以总熵中的电子振动熵SEv代替固态熵 .导出了Co与氢同位素气体反应的ΔH 、ΔG 、ΔS 及平衡氢压力与温度的关系 .CoH的室温下平衡离解压力很低 ,表明CoH是一种稳定的氢化物 ,这与CoH分子的D 0 很大的实验事实一致 .     

Al2O3X(X=H,D,T)的电子振动近似理论方法研究

用密度泛函理论(DFT)方法在6-311 G(d,p)水平上对Al2O3X(X=H,D,T)分子较低能量的几何构型进行了优化.计算结果表明该分子有两个可能基态,即Al2O3X(X=H,D,T)(2A′)Cs和Al2O3X(X=H,D,T)(2B2)C2v.全电子计算了氢同位素分子及Al2O3X(X=H,D,T)的能量E、定容热容CV和熵S.应用电子振动近似理论,即用单个分子Al2O3X(X=H,D,T)中的电子和振动能量和熵近似代表它们处于固态时的能量和熵,计算得到固体Al2O3的氢化热力学函数ΔH0,ΔS0,ΔG0以及平衡压力与温度的关系.当Al2O3吸附氢(氘,氚)形成C2v对称性气态Al2O3X(X=H,D,T)对应的固体时,氢气可以排代氘气,氘气可以排代氚气.这种排代效应非常不明显;形成Cs对称性气态Al2O3X(X=H,D,T)对应的固体时,反应的氢氘氚排代效应的顺序为氚排代氘,氘排代氢,与钛等的氢氘氚排代效应的顺序相反.总体而言,这种排代效应都非常弱.随着温度的增加,这一系列反应的氢氘氚排代效应趋于消失.     

氢化氧化铝的同位素效应研究

在B3LYP/6-311++G(d,p)水平上预测了Al2O3H3分子的较低能量构型.其基态构型具有C s对称性,电子态为1A′.通过研究Al2O3M3和M2(M=H,D,T)的能量E、定容热容C V和熵S,用电子振动近似讨论了Al2O3+3/2M2→Al2O3M3反应的氢同位素效应,得到了Al2O3氢化的热力学函数?H0,?S0,?G0,及平衡压力与温度的关系.研究表明,氧化物Al2O3吸附氢(氘,氚)反应的同位素排代效应顺序为氚排代氘,氘排代氢,与钛等金属的同位素排代顺序相反.但排代效应都非常弱,且随着温度的增加趋于消失.     

A12O3X2（X=H，D，T）的电子振动近似方法

用密度泛函理论在B3LYP／6．311＋＋g（d,P）基组水平上对A12O3X2（X=H,D,T）分子的可能较低能量构型进行了几何优化．结果表明该分子的基态电子态和对称性为A12O3X2（X=H,D,T）（1A’）G,计算了氢同位素分子及A12O3X2（X=H,D,T）的电子能量E、定容热容Cv和熵S．用电子振动近似方法计算了固体A12O3的氢化热力学函数△H0,△S0,△G0,以及平衡压力与温度的关系．当A1203吸附氢（氘,氚）形成固体时,反应的氢氘氚排代效应的顺序为氚排代氘,氘排代氢,与钛等金属与氢及其同位素反应的氢氘氚排代效应的顺序相反．总体来说,这种排代效应都非常弱．随着温度的增加,这系列反应的氢氘氚排代效应趋于消失．     

(ZnSe)n(n=1,2)团簇结构及ZnSe分子热力学性质的理论计算

用密度泛函B3LYP方法、6-311 G基组对(ZnSe)n(n=1,2)分子体系进行了理论研究,得到(ZnSe)n(n=1,2)分子体系的基态电子状态的平衡几何Re、谐振频率、偶极矩和离解能De及不同温度、压力下的热力学函数值;设用总能量中的电子和振动能量近似代表ZnSe分子处于固态时的能量,用总熵中的电子和振动熵近似代表ZnSe分子处于固态时的熵,进而计算了Zn与Se反应的ΔH0、ΔS0、ΔG0,并由此计算出不同温度的反应平衡常数Kp.结果表明:在298~1150 K温度范围内,Zn与Se反应的自由能值均为负,且随着温度的升高,ΔG0值负的越多,表明在这个温度范围内反应能自发发生,而且自发趋势随温度的升高逐渐增大;平衡常数逐渐减小,即反应进行程度随温度的升高逐渐减小;ZnSe分子材料的导电性随压力增大而增强.     

PuN基态分子势能函数与热力学函数的理论计算

在Pu的相对论有效原子实势近似和N原子 6 - 311G 全电子基函数下 ,用密度泛函B3LYP方法计算得到PuN分子基态X6Σ+ 的结构与势能函数、力常数与光谱数据 .同时计算得到PuN(g)分子在 2 98K时的标准生成热力学函数ΔfH0 、ΔS0 和ΔfG0 ,分别为 - 4 87.2 39kJ/mol、95 .345J/molK和 - 5 15 .6 6 6 1kJ/mol.     

金属镍吸附氢同位素的量子力学计算

根据原子分子反应静力学与群论，确定了ＮｉＨ、ＮｉＤ和ＮｉＴ的基电子状态为２Σ＋。应用基函数６－３１１Ｇ和组态相关ＣＩ或ＱＣＩＳＤ方法，计算了氢同位素分子及其镍化物的能量Ｅ、定容热容Ｃｖ和熵Ｓ。设用总能量中的电子和振动能量近似代表ＮｉＨ、ＮｉＤ和ＮｉＴ分子处于固态时的能量，用总熵中的电子和振动熵近似代表这些分子处于固态时的熵，进而计算了镍吸附Ｈ２、Ｄ２和Ｔ２分子过程的ΔＨ°、ΔＳ°、ΔＧ°和平衡压力，并导出它们与温度的函数关系。计算指出了同位素分子效应，结果合理。所以，本文所建议的用量子力学方法计算多相化学反应，有应用参考价值。     

气固氢化反应热力学函数计算的近似方法

在有效原子实势近似下, 采用Gaussian 98程序及B3LYP/SDD密度泛函方法计算得到了ZrCo和ZrCoH分子的结构及能量E、熵S. 在此基础上, 近似以气态分子总能量中的振动能Ev代替该分子处于固态时的振动能量, 以电子运动和振动运动熵Sev代替分子处于固态的熵, 计算了不同温度下固态ZrCo与H2, D2, T2反应的热力学函数ΔH, ΔG, ΔS及氢化反应平衡压力, 导出了氢化反应温度与平衡压力的依赖关系. 计算得出ZrCoH, ZrCoD, ZrCoT的生成焓(398-598 K)分别为82.81 , 81.54和80.49kJ/mol, 与实验结果很好符合.     

2091铝-锂合金固态氢含量的测定

运用ＲＨ－４０２测氢仪测定具有高挥发性锂的铝－锂合金的固态氢含量具有相当难度。本文就如何鉴别体内氢和表面氢、如何选择加热功率和加热时间及试样大小做了大量探索实验,初步形成了可行的铝－锂固态氢含量的分析方法。同时就测量的误差来源及测氢过程中应注意之点进行了讨论。结果重复性好,且结果比较准确（利用俄罗斯铝－锂合金氢标样比较）。     

Tripyrrylmethane based 2D porous structure for hydrogen storage

The key to hydrogen storage is to design new materials with light mass, large surface and rich adsorption sites. Based on the recent experimental success in synthesizing tripyrrylmethane, we have explored Ti-tripyrrylmethane based 2D porous structure for hydrogen storage using density functional theory. We have found that the structure is stable, and the exposed Ti sites can bind three hydrogen molecules with an average binding energy of 0.175 eV/H₂, which lies in the energy window for storage and release of hydrogen in room temperature and at the ambient pressure.     

Raman spectroscopy of hydrogen‐arsenate group (AsO3OH) in solid‐state compounds: cobalt mineral phase burgessite Co2(H2O)4[AsO3OH]2·H2O

Raman spectrum of burgessite, Co₂(H₂O)₄[AsO₃OH]₂· H₂O, was studied, interpreted and compared with its infrared spectrum. The stretching and bending vibrations of (AsO₃) and As‐OH units, as well as the stretching, bending and libration modes of water molecules and hydroxyl ions were assigned. The range of O H···O hydrogen bond lengths was inferred from the Raman and infrared spectra of burgessite. The presence of (AsO₃OH)²⁻ units in the crystal structure of burgessite was proved, which is in agreement with its recently solved crystal structure. Raman and infrared spectra of erythrite inferred from the RRUFF database are used for comparison. Copyright © 2010 John Wiley & Sons, Ltd.     

Vibrational analysis of NaM2OH(H2O)(MoO4)2/D2O [M=Ni,Zn]

The infrared and Raman spectra of NaNi₂OH(H₂O)(MoO₄)₂ and NaZn₂OH (H₂O)(MoO₄)₂ and their partially deuterated analogues are recorded and analysed on the basis of vibrations of MoO ₄ ²⁻ tetrahedra and H₂O molecules. The MoO ₄ ²⁻ groups are found to be more distorted in NaNi₂OH(H₂O)(MoO₄)₂ than in the other compound. Bands indicating the presence of H₃O⁺ ions are not observed in NaZn₂OH(H₂O)(MoO₄)₂ ruling out the possibility of the formulation of NaZn₂OHO(MoO₃OH)₂. Hydrogen bonds of medium strength are present in both the compounds.     

CO2活化温度对碳气凝胶结构及氢吸附性能影响

 以间苯二酚(R)和甲醛(F)为前驱体制备出RF碳气凝胶,并利用CO₂气体对其进行活化,通过热重分析(TG)、X射线衍射(XRD)、氢吸附等表征手段研究了活化过程中温度对碳气凝胶微结构及氢吸附性能的影响。结果表明：CO₂活化可使碳气凝胶比表面积大幅提高,且不会影响其微孔网络结构。随着活化温度的升高,碳气凝胶非晶性变得更加明显,失重率显著增加,微孔体积、比表面积及氢吸附量先增后减,有望通过改变CO₂活化温度增加碳气凝胶微孔数量来提高其氢吸附性能。     

The catalytic effects of H2CO3, CH3COOH,HCOOH and H2O on the addition reaction of CH2OO + H2O → CH2(OH)OOH

The addition reaction of CH₂OO + H₂O → CH₂(OH)OOH without and with X (X = H₂CO₃, CH₃COOH and HCOOH) and H₂O was studied at CCSD(T)/6-311+ G(3df,2dp)//B3LYP/6-311+G(2d,2p) level of theory. Our results show that X can catalyse CH₂OO + H₂O → CH₂(OH)OOH reaction both by increasing the number of rings, and by adding the size of the ring in which ring enlargement by COOH moiety of X inserting into CH₂OO···H₂O is favourable one. Water-assisted CH₂OO + H₂O → CH₂(OH)OOH can occur by H₂O moiety of (H₂O)₂ or the whole (H₂O)₂ forming cyclic structure with CH₂OO, where the latter form is more favourable. Because the concentration of H₂CO₃ is unknown, the influence of CH₃COOH, HCOOH and H₂O were calculated within 0–30 km altitude of the Earth's atmosphere. The results calculated within 0–5 km altitude show that H₂O and HCOOH have obvious effect on enhancing the rate with the enhancement factors are, respectively, 62.47%–77.26% and 0.04%–1.76%. Within 5–30 km altitude, HCOOH has obvious effect on enhancing the title rate with the enhancement factor of 2.69%–98.28%. However, compared with the reaction of CH₂OO + HCOOH, the rate of CH₂OO···H₂O + HCOOH is much slower.     

Theoretical study of the reaction of H2 with a Cu2Pt2 cluster

The study of the interaction of a pyramidal tetramer of Cu₂Pt₂ with the H₂ is reported here through ab initio multiconfigurational self-consistent field (MC-SCF) calculations, plus extensive multireference configuration interaction (MR-CI), variational and perturbative calculations. The lowest three electronic states X ¹A′, a ³A′ and a ¹A′ of the bare cluster were considered in order to study this interaction. For the H₂ C_s approaching a Pt vertex, results show that the Cu₂Pt₂ pyramid cluster in its X ¹A′ and a ¹A′ states can spontaneously capture and dissociate the H₂. For the H₂ C_s approaching a Cu vertex, where H₂ is located in the C_s reflecting plane, the Cu₂Pt₂ cluster in its X ¹A′ electronic state shows capture of the hydrogen molecule after surmounting an energy barrier; moreover, in this approach the Cu₂Pt₂ cluster in its a ¹A′ electronic state shows spontaneous capture of the hydrogen molecule. For the H₂ approaching a Cu vertex, where the C_s reflecting plane bisects the H₂ molecule, the Cu₂Pt₂ cluster in its three lowest-lying states is able to capture the hydrogen molecule after surmounting a small barrier. The Cu₂Pt₂+H₂ C_s face-on interactions show a lower H₂ activation than that which was obtained in the equivalent Pt₄+H₂ interactions.