基于流体-磁流体-粒子混合方法的高空核爆炸碎片云模拟

提出了描述高空核爆炸碎片云运动的流体-磁流体-粒子(particle-in-cell, PIC)混合模型,相较目前的主流模型,该模型能够计算更加广泛的空间尺度.根据碎片云运动涉及的高温离子、低温离子和中性大气的不同性质,采用三种模型进行联合求解:高温离子用PIC粒子模型计算,低温离子用磁流体模型计算,中性大气用流体模型计算,并将三者之间的相互作用作为源项加入相应的控制方程.最后,计算了美国Starfish试验中碎片云的扩展情况,与试验结果进行了比对,并验证了求解方案的可靠性.此外,还给出了不同投影角度下碎片云形状随时间的变化,并分析了影响碎片云运动的主要因素,包括大气阻力、磁压、槽型不稳定性和霍尔电流等.     

1-碘丙烷分子的电子动量谱学研究：自旋-轨道耦合效应与分子内轨道相互作用

利用不对称不共面电子动量谱仪,在2.5 keV碰撞能量下,采用高精度的SAC-CI方法计算了1-碘丙烷分子束缚能谱,同时采用Hartree-Fock、B3LYP/aug-cc-pVTZ(C,H)6-311G^**(I)方法计算其电子动量分布. 并对电离能峰进行了标示. 结合非相对论与相对论计算方法以及自然键轨道分析,对最外层两个轨道(碘的5p孤对)的自旋-轨道耦合效应与分子内轨道相互作用进行了比较. 两种相互作用对电子动量分布的不同影响是可观的. 实验结果与相对论计算的结果一致,表明1-碘丙烷分子内自旋-轨道耦合效应占主导.     

C20分子与C20-、C202-离子的特性分析与比较

应用密度范函理论(DTF)的B3LYP方法,在6-31G*基组水平上对C1对称C20富勒烯分子及C20-、C202-离子进行了几何结构的全局优化、频率以及自然键轨道分析计算(NBO),然后对三者的几何构型、稳定性、振动光谱等做了分析和比较.研究表明:离子的键长普遍比分子的键长长,C20-离子的稳定性最高.C202-离子的红外峰值较大,C20-离子的拉曼光谱峰值较大,振动光谱可以用来作为区分三者的手段.     

3-氨基-2,5-二氯苯甲酸振动光谱的密度泛函研究

为了本质地把握3-氨基-2,5-二氯苯甲酸(3A2,5DBA)的振动光谱和结构间的关系,在HF和B3LYP水平上利用6-311G(d,p)基组对3A2,5DBA进行了结构优化和振动频率的计算,得到了3A2,5DBA的结构信息和全部45个简正振动模式.通过与苯甲酸的结构参数以及相关文献数据的对比,发现B3LYP/6-311G(d,p)方法较HF/6-311G(d,p)方法能给出更加合理的结果.考虑到计算模拟分子和实验测量样品间的差异,对计算所得到的频率进行了合理的标度修正.在B3LYP/6-311G(d,p)方法下,对波数小于800cm-1的振动频率,标度因子取1.001 3,而波数大于800 cm-1的标度因子取0.961 3.借助Gaussian View程序包对所计算得到的振动模式进行了高精度指认,对3A2,5DBA的主要官能团及取代基团进行了振动分析.通过和实验测量的FTIR数据的比对,发现经标度修正后的计算结果和实验测量符合的很好.同时结合相关的文献报道,表明所做的振动指认和振动分析是合理的.     

三甲基苯基六氟磷酸铵离子液体结构性质的密度泛函研究

离子液体以其独特性质广受关注，人们对其潜在的利用价值做了大量的研究.本文采用密度泛函（DFT）B3LYP/6-31(d)的方法计算了三甲基苯基六氟磷酸铵离子液体的几何和电子结构，对比对了三种不同的优化结构.通过自然键轨道(NBO)分析，得到各原子的电荷分布，并用二阶微扰稳定化能分析了阴阳离子间相互作用.结果发现：阴离子分布在阳离子周围的三个区域，所有离子对中阴阳离子间有电荷的转移，且都存在多重氢键作用，阴阳离子间的电荷转移主要是通过LPF→σ*C-H 相互作用.     

SO-2(2B1)离子的结构与势能函数

用二次组态相互作用方法 ,在 6 31 1G(d)基组水平上对SO-2 离子进行了理论计算 ,得到了它的结构、能量、谐振频率和力学性质 ,其结果与实验值符合得非常好 .在此计算的基础上 ,应用多体展式理论方法推导出SO-2 离子的解析势能函数 ,该函数正确反映了SO-2 离子的结构特征和能量变化     

CH3O (X2 E)中电子-振动-自旋耦合能级的理论计算

基于透热模型,采用量子化学从头计算法研究了CH₃O(X²E)自由基中电子-振动-自旋轨道相互作用.透热势能面通过CASPT2/cc-pVTZ方法计算获得.通过对比实验数据,计算得到的电子-振动-自旋能级较以往的报道获得了更精确的计算结果. 关键词： 透热模型 姜-泰勒效应 电子-振动-自旋耦合     

2-甲基-2-丙烯-1-醇的光电离解离研究

利用可调谐真空紫外同步辐射和分子束实验装置在8.0～15.5 eV的光子能量范围内,研究2-甲基-2-内烯-1-醇的光电离解离.测出母体离子和碎片离子:C_4H_8O~+、C_4H_7O~+、C_3H_5O~+、C_4H_7~+、C_4H_6~+、C_4H_5~+、C_2H_4O~+、C_2H_3O~+、C_3H_6~+、C_3H_5~+、C_3H_3~+、CH_3O~+和CHO~+的光电离效率曲线,并获得母体分子的电离能和碎片离子的实验出现势.在B3LYP/6-31+G(d,p)理论水平上,计算光电离过程中母体分子、过渡态和中间体的稳定结构.采用CCSD(T)/cc-pVTZ耦合簇方法计算零点能,得到母体电离能和碎片离子的出现势.通过实验和理论研究,提出2-甲基-2-丙烯-1-醇的光解离路径,分子内氢转移是其中大部分解离途径中的主要过程.     

聚铜络合物[Cu(L)μ-1,3-N3]n(ClO4)n的密度泛函计算及磁性研究

基于广义梯度近似密度泛函和全势能线性缀加平面波方法,本文对聚铜络合物[Cu(L)μ-1,3-N3]n(ClO4)n(其中L=tridentate Schiff base为三齿席夫基)的态密度和磁矩进行了计算.磁矩计算结果表明:①该聚铜络合物晶体格子的总磁矩为1.00 μB;②中心铜原子(离子)具有最大的原子磁矩,为0.531 μB;③铜原子和它周围最邻近的氮原子的原子磁矩是该聚铜络合物晶体格子总磁矩的主要来源.通过对中心铜原子及其最邻近氮原子的自旋态密度图进行分析,得出了铜原子和它周围最邻近氮原子的磁性主要分别来源于它们的d轨道和p轨道,同时还发现了中心铜离子的d轨道与叠氮末端氮原子的p轨道之间存在杂化现象, 以及中心铜离子向叠氮末端氮原子的自旋退局域化现象.自旋退局域化效应通过叠氮这一旁道使相邻两中心铜离子发生铁磁性相互作用.     

Xe10+离子EUV发射谱的理论研究

利用组态相互作用方法和扭曲波近似方法系统地计算了Xe10 离子的能级、振子强度、辐射跃迁速率以及电子碰撞强度.用得到的原子参数模拟了冕平衡条件下Xe10 离子EUV(Extreme Ultra-violet)波段(5~20nm)的发射谱,发射谱的波长位置和相对强度与实验结果符合得较好.研究表明:在较宽的等离子体条件范围内,发射谱的相对强度对温度和密度不敏感.     

2-氨基吡啶气相氟代反应的密度泛函理论研究

采用量子化学方法,运用密度泛函理论(DFT)B3LYP方法,在6-311G*基组水平上,以2-氨基吡啶为起始反应物,全优化计算了亚硝酰阳离子NO~+对2-氨基吡啶中氨基进攻的重氮化反应及氟硼酸根阴离子BF_4~-对吡啶重氮正离子进攻的席曼反应的机理,搜索到整个反应过程中的过渡态结构,得到了反应路径并通过IRC验证,并对各反应中间体、过渡态和产物进行分子几何构型优化、振动频率分析和标准热力学函数计算.通过计算,搜索到的过渡态均为环状结构,与配位插入反应类似,利于原子间化学键的断裂及新键的形成;通过热力学及动力学计算,重氮化-席曼反应是剧烈的放热反应,与实验结果相吻合.     

The study on interactions between 1‐ethyl‐3‐methylimidazolium chloride and benzene/pyridine /pyrrole/thiophene

The density functional theory was used to investigate the interactions between 1‐ethyl‐3‐methylimidazolium chloride ([EMIM]Cl) and benzene/pyridine/pyrrole/thiophene. The complexes formed between [EMIM]Cl and benzene/pyridine/pyrrole/thiophene were optimized at the ωB97XD/6‐31++G** level, and the optimized complexes were further analyzed by natural bond orbital, atoms in molecules, and noncovalent interaction. The calculated results show that the interaction energy between ionic liquid and benzene/pyridine/pyrrole/thiophene is in the order pyrrole > pyridine > thiophene > benzene. The major interactions between ionic liquid and benzene/pyridine/pyrrole/thiophene are hydrogen bonding and π‐π interaction, accompanied by C···H, N···H, H···H, and S···H weak interactions. Both cation and anion of ionic liquid are involved in interactions with aromatic compounds.     

Multiscale modelling strategies and experimental insights for the solvation of cellulose and hemicellulose in ionic liquids

ABSTRACT

The present study investigates the dissolution behaviour of cellulose and hemicellulose in potential ionic liquids (ILs) using both the quantum chemical and experimental validation. For converging upon the recommended IL, 1428 ILs consisting of 42 cations and 34 anions were studied with the conductor like screening model for real solvents (COSMO-RS) model. Based on the infinite dilution activity coefficient of the components in IL, the selected anions and cations were visualised by observing their interactions with cellulose and hemicellulose using interaction energies, natural bonding orbital analysis and molecular dynamics simulations. The dissolution order of cellulose and hemicellulose in ILs was primarily determined by the evaluation of hydrogen bonds between the oxygen atom of anion and hydroxyl proton of cellulose/hemicellulose. From this discernible fact, the anion of the IL was observed to play a leading role in the solvation process as compared to the cation. Eventually, acetate [OAc]^– anion and 1-ethyl-3-methylimidazolium [EMIM]⁺ cation were found to be good candidates for the dissolution of cellulose and hemicellulose. This was further confirmed by the measurement of solid-liquid equilibria with cellulose and hemicellulose. The regenerated cellulose powder was then characterised by Fourier transform spectroscopy(FTIR), X-ray diffraction (XRD) and Thermal gravimetric analysis (TGA).     

N-丁基吡啶四氟硼酸盐/水二元体系的分子动力学模拟研究

利用分子动力学模拟方法研究了离子液体N-丁基吡啶四氟硼酸盐([BPy]BF₄)与Tip4p模型水分子的二元体系的微观结构.比较了各组分间的径向分布函数,结果表明随着离子液体比例的增加,水与阴离子、水与阳离子头部吡啶环、阳离子头部与阴离子上相关原子间的径向分布函数峰值都呈现递增的趋势,而阳离子上丁基链末端碳原子间的径向分布函数没有明显变化;空间分布函数则直观地反映出阴离子主要分布在阳离子的吡啶环周围,水分子在阴离子周围近似呈均等分布,且几率随离子液体比例增大而增加;另外还探讨了不同离子液体比例下的二元体系中氢键的数目和寿命,结果均呈现一定规律的变化.     

气液耦合振动对热声发动机性能的影响

进行了气液耦合振动驻波型热声发动机定量模拟.重点比较分析了单纯气体振动系统和引入[EMIM][BF_4]室温离子液体作为液体活塞的气液耦合振动系统的运行参数,并考察了液体活塞的质量对热声发动机谐振频率、压力振幅以及板叠热端温度等的影响.     

离子液体中聚氧化乙烯(PEO)相变过程中的氢键效应

我们把Flory-Huggins模型推广应用到聚合物/离子液体体系,研究聚氧化乙烯(PEO)在离子液体[EMIM][BF_4]中相变过程中的氢键效应,理论模型考虑了三种类型氢键(Ⅰ型:PEO-[EMIM]~+氢键,Ⅱ型:PEO-[BF_4]~-氢键和Ⅲ型:[EMIM]~+-[BF_4]~-氢键)的形成,分析了三种类型的氢键分数随温度、 PEO体积分数的变化.研究发现,三种类型的氢键分数随温度的升高而减少.在较小PEO体积分数条件下,增加PEO体积分数,Ⅰ型、Ⅱ型氢键分数轻微地减小;在较大PEO体积分数条件下,增加PEO体积分数,Ⅰ型、Ⅱ型氢键分数急剧减少.Ⅲ型氢键分数随着PEO体积分数的增加而急剧降低.由于三种氢键效应,第二维里系数A_2随温度的增加而减小.通过计算分析不同分子量的PEO在[EMIM][BF_4]中的相图发现,在PEO体积分数较低的条件下,Ⅰ型、Ⅱ型和Ⅲ型氢键是PEO相变的主要驱动力;在PEO体积分数较高的条件下,Ⅰ型和Ⅱ型氢键在PEO相变过程中起到主导作用.     

Can tetra‐tert‐butylethylene be formed by ion–ion recombination or ion–molecule reaction of two di‐tert‐butylcarbene units?—a DFT study

The reaction channels of di‐tert‐butylcarbene ( 2 ), its radical anion, ( 3 ) and its radical cation ( 4 ) were investigated theoretically by using DFT/B3LYP with 6‐31+G(d) basis set and 6‐311+G(2d,p) for single point energy calculations. Conversion of the neutral carbene 2 to the charged species 3 and 4 results in significant geometric changes. In cation 4 two different types of C? (CH₃)₃ bonds are observed: one elongated sigma bond called “axial” with 1.61 Å and two normal sigma bonds with a bond length of 1.55 Å. Species 2 and 4 have an electron deficient carbon center; therefore, migration of CH₃ and H is observed from adjacent tert‐butyl groups with low activation energies in the range of 6–9 kcal/mol like similar Wagner–Meerwein rearrangements in the neopentyl‐cation system. Neutral carbene 2 shows C? H insertion to give a cyclopropane derivative with an activation energy of 6.1 kcal/mol in agreement with former calculations. Contrary to species 2 and 4 , the radical anion 3 has an electron rich carbon center which results in much higher calculated activation energies of 26.3 and 42.1 kcal/mol for H and CH₃ migrations, respectively. NBO charge distribution indicates that the hydrogen migrates as a proton. The central issue of this work is the question: how can tetra‐tert‐butylethylene ( 1 ) be prepared from reaction of either species 2 , 3 , or 4 as precursors? The ion–ion reaction between 3 and 4 to give alkene 1 with a calculated reaction enthalpy of 203.5 kcal/mol is extremely exothermic. This high energy decomposes alkene 1 after its formation into two molecules of carbene 2 spontaneously. Ion–molecule reaction of radical anion 3 with the neutral carbene 2 is a much better choice: via a proper oriented charge–transfer complex the radical anion of tetra‐tert‐butylethylene (11) is formed. The electron affinity of 1 was calculated to be negligible. Copyright © 2010 John Wiley & Sons, Ltd.     

Research for improvement on the extract efficiency of lignans in traditional Chinese medicines by hybrid ionic liquids: As a case of Suhuang antitussive capsule

Recently, efficient extraction of natural products from traditional Chinese medicines (TCMs) by green solvents is deemed an essential area of green technology and attracts extensive attentions. In this work, a green protocol for simultaneous ultrasonic-extraction of the native compounds with different polarities of TCMs by using a hybrid ionic liquids (HILs)-water system was reported for the first time. As a case study, three superior ILs (1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]), 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]), and 1-allyl-3-methylimidazolium chloride ([AMIM]Cl)) were chosen as the compositions of the HILs system, and the TCMs Suhuang antitussive capsule (SH) containing different-polarity lignans was selected. Primarily, an ultra-performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UPLC-QqQ-MS/MS) method in the multiple reaction monitoring (MRM) mode was established for qualitative and quantitative analysis of 18 lignans. After majorization by uniform design experiment, the HILs prepared with [AMIM]Cl, [EMIM][BF4], and [EMIM][OAc] at a volume ratio of 1:5:5 could simultaneously extract multi-polarity lignans compared to single IL. Subsequently, the conditions of ultrasonic extraction employing with HILs and traditional organic solvent were optimized by the response surface methodology, respectively. The results indicated that the extract efficiency of the HILs system for target compounds was significantly improved compared with the traditional organic solvent-extraction, i.e. the content of total lignans in ethanol system was up to 47 mg/g, while that in the HILs system was up to 69 mg/g, with an increasing of 47%. Additionally, ¹H-NMR and ¹³C-NMR spectra were used to characterize the hydrogen-bond interactions in the HILs-lignan mixtures. Extraction with the HILs in TCMs is a new application schema of ILs, which not only avoids the use of volatile toxic organic solvents, but also shows the potential to be comprehensively applied for the extraction of bioactive compounds from TCMs.     

稀土硅钨杂多配合物与半菁复合材料的合成及光学性质

通过Keggin结构稀土硅钨杂多配合物K₁₃[Ln(SiW₁₁O₃₉)₂] (其中Ln=La,Ce,Pr,Nd,Sm,简写为Ln(SiW₁₁)₂)与碘化(E)-N-甲基-4-(2-(4-二甲氨基苯基)乙烯基)吡啶(C₁₆H₁₉N₂I,AI)反应,制备了一系列含轻稀土元素的硅钨杂多配合物与半菁衍生物的复合材料。应用元素分析和TG-DTA确定配合物的组成为(C₁₆H₁₉N₂)₁₀K₃[Ln(SiW₁₁O₃₉)₂]。利用红外光谱、紫外-可见光谱和荧光光谱研究了上述复合材料的光学性质及复合材料中无机组分与有机组分间的相互作用。     

NMR determination of dynamic parameters of CH3 groups in P(CH3)4SbCl6

The longitudinal relaxation time T1 and the second moment M2 of 1H NMR line in a wide temperature range have been measured for P(CH3)4SbCl6. It was found that two different methyl groups in each tetramethylphosphonium cation perform two different rates of C3 motions. The reduction of the proton second moment M2 just below the temperature of the phase transition Tc2 = 350 K may suggest that the isotropic tumbling of the whole cation [P(CH3)4]+ is involved in the structural change of the crystal lattice induced by the movements of the [SbCl6]- anion.