4-氨基-3,5-二硝基吡唑二聚体分子间相互作用的理论研究（英文）

在密度泛函(DFT)B3LYP/6-311++G~(**)水平下,求得4-氨基-3,5-二硝基吡唑(LLM-116)二聚体势能面上的4种全优化几何构型.经基组叠加误差(BSSE)和零点能(ZPE)校正,求得分子间最大相互作用能为-29.56 k J·mol~(-1).研究表明,其相互作用是放热过程,并随着温度的升高,相互作用减弱;自然键轨道(NBO)分析揭示了相互作用的本质;对优化构型进行振动分析,得其红外光谱,并基于统计热力学求得200.0-800.0 K温度范围从单分子形成二聚体的热力学性质变化.     

叠氮乙烷二聚体分子间相互作用的理论研究

用abinitioHF/ 6 3 11+ +G 计算求得叠氮乙烷二聚体势能面上三种优化构型和电子结构 .经MP2电子相关校正和基组叠加误差 (BSSE)以及零点能 (ZPE)校正 ,求得分子间最大相互作用能为 -10 .45kJ/mol.二子体系间的电荷转移很少 .由自然键轨道 (NBO)分析揭示了相互作用的本质 .基于统计热力学求得温度为 2 0 0 .0 0～80 0 .0 0K从单体形成二聚体的热力学性质变化     

2-（甲苯-4-磺酰胺基）-苯甲酸的结构、光谱与热力学性质的理论研究

在B3LYP/6-31++G^**水平对2-（甲苯-4-磺酰胺基）-苯甲酸分子进行几何构型优化和频率的计算,得到红外光谱,拉曼光谱和不同温度下的热力学性质.结果显示,该分子羧基的碳氧原子、磺酰胺基的氮原子与苯环形成不同的离域大π键,空间位阻效应和共轭效应使两个苯环不在同一平面,二面角为63.2°.使用含时密度泛函理论方法计算第一激发态的电子垂直跃迁能,得到最大吸收波长为312.7?nm,属于近紫外区,这与该分子在二氯甲烷溶剂中的实验测得值307?nm一致. 关键词： 2-（甲苯-4-磺酰胺基）-苯甲酸 光谱 热力学性质 密度泛函理论     

O3与O3分子间相互作用的理论研究

采用从头算方法,在B3LYP水平下对O3分子单体及其二聚体进行了几何结构优化,得到四种O3分子二聚体的稳定构型,并经MP2法、均衡法(Massage)分别校正了电子相关和基组叠加误差(BSSE),通过对分子中原子间的最短距离,分子间质心距离与各构型相互作用能的关系进行了分析、比较,得到了最稳定的构型,其对应的O3分子二聚体相互作用能为:-8.788 kJ/mol.     

5-羟基-7,4′-二甲氧基二氢黄酮分子结构的理论计算研究

分别应用Hartree—Fock从头算方法和B3LYP密度泛函方法从黑沙蒿中分离得到的5-羟基-7，4’-二甲氧基二氢黄酮分子的几何构型进行优化，并采用规范不变原子轨道GIAO法，进行核磁共振化学位移计算，得到其两种构型的结构参数和NMR化学位移值。并对理论计算值与实验值的误差进行了统计分析、由计算结果推测该化合物分子结构中C（2）上的H在B位，即C（2）的绝对构型为S型．     

3-呋喃甲酸红外光谱及分子间相互作用的理论研究

采用密度泛函理论(DFT)B3LYP/6-311+G(d, p)及二级微扰理论(MP2)MP2/6-311G+(d, p)对3-呋喃甲酸单分子进行构型优化,得到了该分子的两个稳定几何构型,通过计算异构化反应的过渡态,构型Ⅰ转变为构型Ⅱ要克服32.10 kJ·mol~(-1)势垒,异构化反应常温下较难进行。玻尔兹曼分布结果表明常温下低能量的构型Ⅰ百分含量远高于高能量的构型Ⅱ,故常温下以构型Ⅰ的形式存在。在此基础上采用非谐性力场计算了单分子的红外光谱,并计算了振动频率的势能分配比例,指认了相应的振动模式,发现单分子的计算数据与实际气相分子的红外谱图相似,对2 000～2 500 cm~(-1)出现的吸收峰可采用倍频、和频给以解释。对于二聚体,采用考虑分子间弱相互作用校正的M06密度泛函进行模拟,非谐性条件下二聚体的计算结果与固态谱图较为相符, 2 000～3 000 cm~(-1)之间出现的弱吸收峰,对应各种泛频峰,经计算振动量子数对应的0→2红外跃迁的倍频吸收峰强度很小,而基频之间形成的合频是造成这些峰的主因,由于二聚体分子间是通过氢键而不是化学键结合的,其刚性降低,非谐性因素增大,与之相关的合频峰的强度也随之增大,在单体中不太明显的这些峰在二聚体中已很明显,与实验谱图较为吻合。但实际固体中由于存在多种二聚体、多聚体,使得羟基的红外吸收峰变宽且强度降低,另外量子化学理论由于缺乏精准的弱相互作用的计算参数、普适的力场、合理的色散校正项等因素,使得计算结果与实际谱图有一定差距。进一步对该分子的二聚体进行了自然键轨道分析,发现电子给体羰基氧原子与电子受体羟基形成的二级稳定化能为121.4 kJ·mol~(-1),分子间结合能为65.27 kJ·mol~(-1),给体反馈到受体轨道的电荷为0.067个电荷,表明3-呋喃甲酸分子间的相互作用主要来自于形成的分子间氢键。通过计算不同温度下二聚体的吉布斯自由能变,当温度升高到500 K时ΔG值变为正值,二聚体变得不稳定,氢键被破坏,单体分子将以分子间作用力结合在一起。     

1,1-二氨基-2,2-二硝基乙烯晶体热膨胀各向异性的模拟研究

对新型钝感高能炸药组分1,1-二氨基-2,2-二硝基乙烯（FOX-7）,考察并选择了适用的分子力场和超晶胞初始构型,通过303K-378K温度范围在NPT系综下的分子动力学模拟（MD）,得到常压下各温度的FOX-7晶体平衡构型,发现随温度升高晶体内分子的取向和堆积方式不变;通过线性拟合求算出线膨胀系数,发现αb明显较大而αc与αa接近但不相等;接着采用密度泛函理论(DFT)方法随各向棱长膨胀的能量变化进行了模拟计算,发现得到的能量变化成各向异性并与各向热膨胀系数相关,从而建立FOX-7晶体特定分子堆积模式与热膨胀各向异性的关联。     

理论研究F2BN3多聚体的结构特色和热力学稳定性

在密度泛函理论（DFT）B3LYP/6-311+G*水平上计算研究了叠氮二氟硼多聚体(F2BN3)n (n=1-4),获得了它们的结构和热力学性质,讨论了几何参数随聚合度的变化趋势。多聚体(F2BN3)2-4的优化构型均为由不同子体系的叠氮基α−N和B原子相连形成的环状结构。三聚体的船扭式构象比椅式构象的结合能低10.54 kJ•mol-1;四个新获得的四聚体的结合能差异较大,大小为3.1~45.65 kJ•mol-1。由焓变可知,单体形成二聚体在热力学上是不利的,而形成三聚体和四聚体在高达1200 K的温度下是有利的,同时分析比较了后续反应的热力学参数。     

硼、氮取代二聚苯中碳原子导致层间相互作用本质变化研究

在MP2/aug-cc-pVTZ水平下优化了二聚苯及其碳被硼、氮原子取代的几何构型;计算了这些二聚体的CCSD(T)/CBS相互作用能;并用SAPT2+/aug-cc-pVDZ分析了相互作用能成分.探索了硼、氮取代二聚苯中碳原子所导致层间相互作用本质变化.结果表明:稳定构型而言,从苯(C_6H_6)、1-氮-2-硼杂苯(BNC_4H_6)、1,3-二氮-2,4-二硼杂苯(B_2N_2C_2H_6)二聚体的平行移位(PD)构型向无机苯(B_3N_3H_6)二聚体的夹心(S)构型转变,其中C_6H_6和B_3N_3H_6二聚体稳定构型的堆叠型式分别与之相对应的石墨烯(GE)和六方氮化硼(h-BN)2D层间材料的堆叠型式相一致.硼、氮原子取代二聚苯中的碳原子后使其相互作用能增大,其中BNC_4H_6和B_2N_2C_2H_6二聚体的相互作用能增大较为明显.所研究体系二聚体稳定构型均以色散能为主导、静电能次之、诱导能相对较小.硼、氮取代二聚苯中碳原子后其静电能对总吸引能的贡献明显增大.     

新型胺类毒品分子的结构、光谱和热力学性质研究

采用密度泛函理论B3LYP/6-31++G**方法对2-胺基苯基丙烷（a）、2-甲胺-1-苯基丙烷（b）、7-甲氧基- a -甲基-1,3-苯骈二氧杂环戊烯-5-乙胺（c）、2,5-二甲氧基- a -甲基苯乙酰胺（d）四个新型胺类毒品分子进行结构优化,并进行频率和热容、熵、焓、自由能等气态热力学性质计算,获得它们的红外光谱、电子光谱和分子轨道图,模拟出标准摩尔热容Cθpm、标准摩尔熵Sθm、标准摩尔焓Hθm等气态热力学性质与温度之间的函数关系式.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.     

Fiber Modal Index Measurements Based on Fiber Gratings

A novel method based on fiber gratings for measuring the effective indices of fiber modes is proposed. The effective index difference between the core mode and a cladding mode was obtained by analyzing the interference fringe of a pair of cascaded long-period fiber gratings. In order to extract the core mode index from the measured index difference, an index matching oil immersion method is proposed. By analyzing the interaction between the cladding mode and the oil applied on the cladding surface, the mode order and the effective index of the involved cladding mode might be calculated. Experimental results about the interference fringe shifts induced by the oil index and the oil-applied length are also presented.     

Optical Pulse Compression Schemes That Use Nonlinear Bragg Gratings

Nonlinear optical pulse compression of picosecond pulses typically requires long lengths of optical fiber and multiple components. Periodic structures, such as fiber Bragg gratings, are highly dispersive at wavelengths outside of the photonic bandgap. This implies that such gratings can be used as very short all-fiber compressors. In this paper a number of such compression schemes are reviewed involving uniform and nonuniform fiber Bragg gratings, relying on both soliton and nonsoliton compression principles. Experimental results supporting the corresponding underlying theory are also presented. Finally, an extension of one of the compression schemes is shown, which allows the generation of adjustable high-repetition rate soliton trains.