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.     

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

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 kJ×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。     

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.     

HOX(X=F,Cl)二聚体红移氢键的理论研究

用理论方法研究了二聚体HOX(X=F,Cl)分子间氢键，在B3LYP/6-31+G(d,p)、 B3LYP/6-311++G(d,p)、MP2/6-31+G(d,p)和MP2/6-311++G(d,p)水平上，利用标准方法和均衡校正方法对二聚体进行了几何优化、振动频率和相互作用能的计算。同时，利用电子密度拓扑分析和自然键轨道分析对红移氢键的本质进行了分析。研究表明：分子间O—H…O和O—H…X(X=F,Cl)氢键的形成使二聚体中O—H键伸长，伸缩振动频率减小，形成红移氢键。NBO分析表明，电荷转移效应占优势，因此形成O—H…O和O—H…X(F,Cl)红移氢键。     

甲醛与甲酰胺相互作用的从头算研究

在MP2 /6 3 1G(d)和MP2 (FC) /6 3 11+ +G(d ,p)水平上 ,对H2 CO和HCONH2 以及设计的 3种构型H2 CO…HCONH2 复合物等进行几何全优化计算 ,经振动频率分析 ,确认它们为势能超曲面上的稳定驻点 .然后在MP2 /6 3 11+ +G(2df,3p)水平上进行单点能计算和基组重叠误差 (BSSE)校正以获得相互作用能 .并利用自然键轨道理论和分子中的原子理论探讨H2 CO和HCONH2 相互作用的本质 .分子间相互作用的能量分解分析显示 ,静电能在H2 CO…HCONH2 相互作用能中占主导地位     

环五甲撑五硝胺(CRX)结构和性质的DFT预示

用密度泛函理论 (DFT)B3LYP方法 ,在 6 31G 基组水平下 ,全优化计算了环五甲撑五硝胺 (CRX)的分子几何和优化构型下的电子结构 .环C -N键长为 0 .144～ 0 .148nm ,N -NO2 键长为 0 .139～ 0 .142nm ;CRX的最高占有MO(HOMO)能级和最低未占MO(LUMO)能级之间的差值ΔEg(5 .2 0 5 4eV)较大 ,预示CRX较稳定 .基于简谐振动分析求得IR谱频率和强度 .运用统计热力学方法 ,求得在 2 0 0～ 12 0 0K的热力学性质C0p ,m、S0 m 和H0 m.还运用Kamlet公式预示了它的爆速和爆压分别为 916 9m/s和 37.88GPa .     

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。     

ThO+/0/-2不同电荷态对N2O氧化CO反应的影响

本文采用密度泛函理论,对ThO^+/0/-₂团簇参与CO与N₂O间氧化还原反应(CO+N₂O→CO₂+N₂)的机理展开研究,探讨钍氧团簇所带的电荷对该反应的影响.研究表明：ThO^+/0/-₂在反应中主要起传输氧原子的作用,其中ThO⁺₂与CO的反应以及ThO^+/0/-与N₂O的反应都为热力学上的放热反应,而ThO^0/-₂与CO的反应为热力学上的吸热反应.随着电荷态的改变,ThO^+/0/-₂与CO反应的总能垒(E_b)与总驱动力(-ΔG)有较大差异.因此,通过改变ThO₂的电荷态能调节其对CO/N₂O反应的催化活性,综合考虑,ThO⁺₂对...     

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.     

HArF和HNO二聚体相互作用氢键的理论研究

用二阶微扰理论结合6-311+G**、6-311++G**和6-311++G(2d,2p)基组对氢键相互作用二聚体HNO···HArF进行研究．在MP2/6-311+G**、MP2/6-311++G**和MP2/6-311++G(2d,2p)水平上，利用标准方法和均衡校正方法对二聚体进行了几何优化、振动频率和相互作用能的计算．对于相互作用能采用G2MP2方法计算．计算结果表明存在两种稳定的二聚体HNO···HArF结构，在这两种结构中，Dimer I(H···F)比Dimer II(H···O)更加稳定．通过振动频率的计算表明，在Dimer I(H···F)中存在N-H···F蓝移氢键，在DimerII(H···O)中存在Ar-H···O红移氢键，并对蓝移氢键加以确认．利用电子密度拓扑学分析和自然键轨道分析对于氢键红移和蓝移进行了合理解释．     

Self-organization of five species in a cyclic competition game

Cyclic competition game models, particularly the “rock–paper–scissors” model, play important roles in exploring the problem of multi-species coexistence in spatially ecological systems. We propose an extended “rock–paper–scissors” game to model cyclic interactions among five species, and find that two of the five can coexistent when biodiversity disappears, which is different from the “rock–paper–scissors” game. As the number of fingers is five, we named the new model the “fingers” game, where the thumb, forefinger, middle finger, ring finger, and little finger cyclically dominate their subsequent species and are dominated by their former species. We investigate the “fingers” model in two ways: direct simulations and nonlinear partial differential equations. An important finding is that the number of species in a cyclic competition game has an influence on the emergence of biodiversity. To be specific, the “rock–paper–scissors” model is in favor of maintaining biodiversity in comparison with the “fingers” model when the variables (population size, reproduction rate, selection rate, and migration rate) are the same. It is also shown that the mobility and reproduction rate can promote or jeopardize biodiversity.     

Experimental study on downstep in Chinese intonation

Downstep in pitch contour of Chinese Putonghua is examined using subtly designed sentences by controlling tone combinations. The results show both automatic and nonautomatic downstep phenomena exist in Chinese. In non-automatic downstep, low tones compress downwards the pitch range of the following syllables. and the main influence of downstep is on topline. Low tone not only lower the topline behind it, but also raise the high tones before it, the effects are compatible with each other. In automatic downstep, the topline of pitch contour in intonational phrase is presented as a linear downtrend, but it differs among speakers due to the effect of personal stress practice. In comparison with downstep phenomenon in other tone or non-tone languages, the downstep ratio in Chinese is not constant, and the domain of downstep is not limited within the adjacent tones.     

Contrastive analysis on tone between Putonghua and Taiwan Mandarin

The differences of the pitch and duration of Chinese syllables between Putonghua （PTH） and Taiwan Mandarin （TM） were studied. The speech materials to be used are not only isolated syllables, but also sentences. The results reveal that： For the isolated syllables, T1 and T2 in TM are influenced by Minnan dialect, therefore their pitch are lower than those in PTH. T3 is fall-rise in PTH, while it is fall in TM. Moreover, the syllable duration sequence for different tone is T3〉T2〉T1〉T4 in PTH, while it is T1〉T2〉T3〉T4 in TM. For the syllables in sentences, T2 is mid-rise in PTH, while it is mid-level in TM. And the T3 is longer than T4 but shorter than T1 or T2 in PTH, while it is the shortest in TM. Furthermore the effects of prosodic phrase boundary on duration for different tones are almost the same in PTH, but the lengthening part of T1 or T2 is longer than that of T3 or T4 in TM.     

Abelian-Higgs phase of SU(2) QCD and glueball energy

It is shown that SU(2) QCD admits an dual Abelian-Higgs phase, with a Higgs vacuum of a type-Ⅱ superconductor. This is done by using a connection decomposition for the gluon field and the random-direction approximation. Using a bag picture with soft wall, we presented a calculational procedure for the glueball energy based on the recent proof for wall-vortices [Nucl. Phys. B 741(2006)1].     

Signal generation in an isotropic medium in scanning electron acoustic microscope

Based on the research in Ref. [5][Materials Science and Engineering, 1989; A122： 57 63], an improved model of heat source is set up, the different modes of Lamb wave in an isotropic sample generated by a chopped electron beam at frequency f are obtained with integral transform and normal function expansion method, and the output signal of PZT coupled at the back surface of the sample is found out. The generation mechanism of SEAM （Scanning Electron Acoustic Microscopy） signal is discussed. It shows that the SEAM is a near field imaging technique with high spatial resolution and its best lateral spatial resolution is about 2√2α （α is the radius of the focused electron beam）. Some of experimental results of SEAM images are presented in the paper and it shows that the spatial resolution of SEAM is better than 0.5 μm and smaller than the thermal diffusion length of the sample. Therefore the character of near field imaging in SEAM is also proved experimentally.     

High efficiency filtering using two-dimensional photonic crystal coupled cavity structures

Transmission spectra of coupled cavity structures (CCSs) in two-dimensional (2D) photonic crystals (PCs) are investigated using a coupled mode theory, and an optical filter based on CCS is proposed. The performance of the filter is investigated using finite-difference time-domain (FDTD) method, and the results show that within a very short coupling distance of about 3λ, where λ is the wavelength of signal in vacuum, the incident signals with different frequencies are separated into different channels with a contrast ratio of 20 dB. The advantages of this kind of filter are small size and easily tunable operation frequencies.     

Real-time restoration of rotational blurred image using gradient-loading

The key to the restoration of rotational motion blurred image is how to restore the image under a low cost and to correct the irreversibility of the degradation function matrix.Based on the special qualities of degradation function matrix and precise deduction in space-domain, we present a new approach using gradient-loading for restoration of rotational blurred image.By easily adding a gradient operator, the irreversibility of the original matrix is corrected and can be applied for inverse filtering then.Gradientloading is the optimized approach which combines the advantages of both the approaches using constrained least square filtering and traditional diagonal-loading.Compared with the approach using least square filtering, its peak signal-to-noise ratio (PSNR) is improved from 3.18 to 6.46dB, while the computing time is reduced to 1/2-1/3.Experimental results demonstrate the effectiveness, noise-resistibility, robustness, and low complexity of this approach, which make it more suitable for real-time environment.     

All-Optical Logic Device Using Bent Nonlinear Tapered Y-Junction Waveguide Structure

We propose an all-optical logic device made of a bent tapered Y-junction waveguide with a Kerr-type nonlinear interface. It could provide an AND gate, OR gate, and exclusive-OR (XOR) gate. We could obtain different transmission results by adjusting the bending angle. The numerical simulation results show that the device functions as AND, OR, and XOR gates.     

Real-time, continuous-wave terahertz imaging by a pyroelectric camera

Real-time, continuous-wave terahertz (THz) imaging is demonstrated. A 1.89-THz optically-pumped farinfrared laser is used as the illumination source, and a 124 × 124 element room-temperature pyroelectric camera is adopted as the detector. With this setup, THz images through various wrapping materials are shown. The results show that this imaging system has the potential applications in real-time mail and security inspection.