Electronic Absorption Spectra and Third-Order Nonlinear Optical Property of Dinaphtho[2,3-b:2’,3’-d]Thiophene-5,7,12,13- Tetraone (DNTTRA) and Its Phenyldiazenyl Derivatives: DFT Calculations

Third-order nonlinear optical (NLO) materials have broad application prospects in high-density data storage, optical computer, modern laser technology, and other high-tech industries. The structures and frequencies of Dinaphtho[2,3-b:2’,3’-d]thiophene-5,7,12,13-tetraone (DNTTRA) and its 36 derivatives containing azobenzene were calculated by using density functional theory B3LYP and M06-2X methods at 6-311++g(d, p) level, respectively. Besides, the atomic charges of natural bond orbitals (NBO) were analyzed. The frontier orbitals and electron absorption spectra of A-G5 molecule were calculated by TD-DFT (TD-B3LYP/6-311++g(d, p) and TD-M06-2X/6-311++g(d, p)). The NLO properties were calculated by effective finite field FF method and self-compiled program. The results show that 36 molecules of these six series are D-π-A-π-D structures. The third-order NLO coefficients γ (second-order hyperpolarizability) of the D series molecules are the largest among the six series, reaching 107 atomic units (10-33 esu) of order of magnitude, showing good third-order NLO properties. Last, the third-order NLO properties of the azobenzene ring can be improved by introducing strong electron donor groups (e.g. -N(CH3)2 or -NHCH3) in the azobenzene ring, so that the third-order NLO materials with good performance can be obtained.

Nonlinear interactions among internal tidal waves in the northeastern South China Sea

We used a set of 75-day long ADCP data from the northeastern South China Sea(SCS) to investigate nonlinear interactions among freely propagating internal tidal waves.The kinetic energy spectra displayed significant peaks at some higher tidal frequencies,such as O1M2(O1+M2),and M4(M2 +M2),where O1 is the lunar diurnal internal tide,M2 is the lunar semidiurnal internal tide,and M4 is the first higher harmonic frequency of M2.These higher tidal harmonic frequency peaks,as well as the fundamental tidal harmonic peaks,show a σ-2.3 spectral falloff rate with frequency.In addition,we explored the possible generation mechanism of higher tidal harmonics.Analysis on the rotary and bicoherence spectra suggests that strong forced non-resonant interaction induced by nonlinear advections was the dominant physical mechanism that induced these higher tidal harmonics.Moreover,the energetic,freely propagating semidiurnal(M2) internal tidal wave played the most crucial role in these interactions.These results indicate that strong nonlinear forced non-resonant interactions among internal tides can be one of the processes responsible for the redistribution of energy in the internal wave spectrum.

Second-Order Analytic Solutions of Nonlinear Interactions of Edge Waves on A Plane Sloping Bottom

Based on the full water-wave equation, a second-order analytic solution for nonlinear interaction of short edge waves on a plane sloping bottom is presented in this paper. For special ease of slope angle β = π/2, this solution can reduced to the same order solution of deep water gravity surface waves traveling along parallel coastline. Interactions between two edge waves including progressive, standing and partially reflected standing waves are also discussed. The unified analytic expressions with transfer functions for kinematic-dynamic elements of edge waves are also given. The random model of the unified wave motion processes for linear and nonlinear irregular edge waves is formulated, and the corresponding theoreti- cal autocorrelation and spectral density functions of the first and the second orders are derived. The boundary conditions for the determination of the parameters of short edge wave are suggested, that may be seen as one special simple edge wave excitation mechanism and an extension to the sea wave refraction theory. Finally some computation results are demonstrated.

Raman Spectra and Crystallographic Properties of a New NLO Material,ZnCd(SCN)_4 Crystal

The crystallographic properties and R aman spectra of the title compound ZnCd(SCN) 4, which is a new nonlinear optica l crystal(NLO), are reported for the first time. This crystal is orthorhombic and its space group is I - 4 with unit cell parameters a =1.113 5(0.2) nm, c =0.437 60(1) nm. There are two formulas per unit cell. Raman spectra of zinc cadmium thiocyanatec (ZCTC) are given and the electron activities in the crystal are shown.

Effect of the nonlinearity of the CCD in Fourier transform profilometry on spectrum overlapping and measurement accuracy

In Fourier transform profilometry （FTP）, we must restrain spectrum overlapping caused by the nonlinearity of the charge coupled device （CCD） and increase the measurement accuracy of the object shape. Firstly, the causes of producing higher-order spectrum components and inducing spectrum overlapping are analysed theoretically, and a simple physical ex- planation and analytical deduction are given. Secondly, aiming to suppress spectrum overlapping and improve measurement accuracy, the influence of spatial carrier frequency of projection grating on them is analysed. A method of increasing the spatial carrier frequency of projection grating to restrain or reduce the spectrum overlapping significantly is proposed. We then analyze the mechanism of how the spectrum overlapping is reduced. Finally, the simulation results and experimental measurements verify the correction of the proposed theory and method.

基于多层面改进多域法的航行船舶时域水动力分析

针对航行船舶三维时域水动力分析问题,本文采用多域高阶边界元法(MDHOBEM, Multi-Domain Higher Order Boundary Element Method)开展研究,通过假设控制面,将计算域分为内域和外域两部分,内域采用Rankine面元法,外域使用自由面格林函数法,内外域联立求解。从内域、外域、波浪激励三个层面改进多域法的精度、计算效率,以适应不同工况需求。内域重新推导非线性边界条件,考虑入射波对绕辐射问题计算的影响,提高大幅波浪中运动计算精度;外域采用垂向积分形式自由面格林函数,提高格林函数积分计算的收敛性、稳定性及计算效率;波浪激励采用高阶谱(HOS, High Order Spectral)方法生成演化的波场,考虑波浪自身的非线性,提高对非线性现象的捕捉和模拟能力。以C11船为对象,研究内域非线性改进对船舶大幅运动计算精度的提高;以S175集装箱船为对象,验证外域垂向积分对运动及波阻增加计算效率和稳定性的提高;对比S175在线性波场和非线性波场中的运动,论证考虑非线性波场对运动计算的影响;以某内倾船为对象,研究不同层次改进对参数横摇现象捕捉的影响,验证非线性波浪激励对多域法非线性现象捕捉能力的提升;整体上形成不同层面改进多域法,为不同工况下时域水动力分析提供理论和程序支撑。

基于共掺杂调控C_(32)多极矩的二阶非线性光学响应

基于密度泛函(DFT)理论,采用CAM-B3LYP方法,以C_(32)分子为多极矩构建骨架,设计了两类替位式共掺杂的富勒烯衍生物C_(28)B_(2)N_(2)和C_(28)B_(2)P_(2),共16种同分异构体,并对它们的电子性质、线性极化率α和一阶超极化率β进行研究。结果表明,掺杂后分子的HOMO-LUMO能隙变小,C_(28)B_(2)P_(2)的α和β值均大于C_(28)B_(2)N_(2)系列。其中偶极分子具有大的β值,八极分子则有较小的β值,筛选出具有优异的二阶非线性光学(NLO)响应特性的结构。含时密度泛函理论(TD-DFT)的结果表明,与C_(32)相比,掺杂后所有结构的吸收光谱的响应范围变宽,最大吸收强度减弱,且最大吸收波长的位置发生红移或蓝移。基于完全态求和(SOS)方法,分别用二能级或三能级公式解释了两类共掺杂结构中β值最大的来源,并且证明了与之有关的电子激发类型为π→π*激发。

非线性系统中双频光栅相位测量

为了在非线性测量系统中获得更好的相位测量结果,提出了一种在几乎消除非线性影响后使用双频光栅投影的相位测量方法。首先,讨论了相位测量系统的非线性效应,分析了频域中存在高阶频谱成份的基本原因,给出了减小非线性效应并分离基频信息的基本方法。然后,在减小系统非线性效应影响的基础上,分析了使用双频光栅投影测量被测物体条纹图像的相位基本原理。为验证所提出的相位测量方法的有效性,进行了计算机仿真和实际实验,获得了良好结果。在仿真实验中,该方法的误差值为有非线性影响方法的27.97%,为几乎没有非线性影响方法的52.51%;在实际实验中,该方法的相位恢复效果最好。表明采用本文方法所测量的相位效果好,误差较小。

应用邻近强震动站点主余震记录的场地及地形效应分析

2022年01月08日青海门源发生M_(S)6.9级地震,在震源相同、路径类似的条件下,间距5.5 km的地震烈度仪站点观测到的地震动加速度存在较大差异,针对此现象,应用主余震强震动记录,分别使用谱比法和标准谱比法分析了场地效应与地形效应对地震动的影响,并提出了通过移动带通滤波器的高频截止频率来确定地面峰值加速度(peak ground acceleration,PGA)的主要贡献频段的方法。考虑场地效应和地形放大效应等因素,在不同频带内初步分析了PGA偏差较大的原因。

2,5-取代基-3,4-C_(60)吡咯衍生物的电子光谱和非线性光学性质规律的理论研究

利用量子化学半经验 AM1及 ZINDO方法研究了 2 ,5 -取代基 -3 ,4-C6 0 吡咯衍生物的结构规律和光谱性质 .以全自由度优化几何构型为基础 ,计算了化合物的电子光谱 .几种化合物在 40 0 nm以上均产生非 C6 0特征吸收 ,结果与实验值一致 ,并对电子跃迁进行了指认 ,分析了光谱红移的原因 .同时用 INDO/ CI-SOS方法计算了它们的二阶非线性光学系数 ,其 βμ 值在 -3 0 .1 4× 1 0 - 30～ -65 .49× 1 0 - 30

巴比妥酸苯胺取代衍生物二阶非线性光学性质和电子光谱的INDO/CI研究

利用量子化学密度泛函理论 (DFT)B3LYP方法 ,在 6 3 1G 基组下对巴比妥酸苯胺取代衍生物体系BA1～BA5进行几何结构优化 .以优化后的构型为基础 ,应用INDO/CI方法进行电子光谱计算 ,并结合实验数据进行了分析 .同时应用完全态求和 (SOS)公式计算二阶非线性光学 (NLO)系数 βμ.设计的系列体系中 βμ 最大值可达到 65 .47× 10 -3 0 esu .进一步探讨了体系的共轭性和烷基取代基链的长度对二者的影响 ,结果表明 ,体系的共轭程度越高 ,烷基取代基的链长度越长 ,体系 βμ值越大 。

9-(4,5-二硫甲基-1,3-二硫杂环戊烯-2-甲叉基)蒽-10(9H)-酮的合成及量子化学计算

设计合成了一种新的具有D π A结构的有机分子 ,9 (4 ,5 二硫甲基 1,3 二硫杂环戊烯 2 甲叉基 )蒽 10 (9H) 酮(C19H14 OS4) .以1HNMR ,FTIR ,元素分析和UV vis进行了表征 .运用Gaussian 98量子化学程序包 ,采用B3LYP密度泛函(DFT)的方法 ,在 6 3 1G(d)水平上对分子的几何构型进行了优化 ,在优化的基础上用TDDFT的方法计算了化合物的电子光谱 ,计算值与实验值基本吻合 .用TDHF的方法计算了它的二阶非线性光学系数 ,与蒽醌相比 ,其第一超极化率 β较大 ,为12 .0 3× 10 -3 0 esu .

取代吡啶系列分子的光谱和二阶非线性光学性质的理论研究

采用ＡＭ１ 方法优化分子构型， 用ＺＩＮＤＯ方法研究了氨基、硝基取代的吡啶系列分子的电子光谱， 并在此基础上用自编程序计算了这些分子的二阶非线性光学系数， 对取代吡啶系列分子的二阶非线性光学系数的影响因素进行了探讨， 并在微观上给予了解释．

混沌同步及其在保密通信中的应用

在全面阐述混沌同步的目的和方法的基础上,提出了一种典型的可用于安全通信的滞同步加密方案,计算机仿真显示了方案的有效性。最后给出三种同步通信安全分析方法并用于方案的安全性研究。

螺旋共轭化合物及其相对应的多烯及联苯连接化合物的结构、光谱和二阶非线性光学性质的比较研究

用ＡＭ１和ＩＮＤＯ／ＣＩ方法研究了螺旋共轭化合物Ⅰ的结构和电子光谱，并在此基础上，用完全态求和公式（ＳＯＳ，自编程序）计算了二阶非线性光学系数βμ．把结果与其对应的多烯及联苯连接的化合物Ⅱ和Ⅲ用同一方法计算得到的结果加以比较，发现螺旋共轭化合物Ⅰ的二阶非线性光学系数βμ虽然小于Ⅱ和Ⅲ。

C_(59)(C_6H_4OCH_3)N的结构、光谱和二阶非线性光学性质的理论研究

用 INDO系列方法对由 (C5 9N) 2 和苯甲醚合成的衍生物 C5 9(C6 H4OCH3) N进行了理论研究 ,得到了分子的稳定构型 .结果表明 ,C5 9(C6 H4OCH3) N具有 Cs对称性 .以优化构型为基础讨论了分子的 UV-Vis光谱、NMR谱线数 ,结果与实验符合得很好 .本文还计算了 C5 9(C6 H4OCH3) N的二阶非线性光学系数 βμ。

土层非线性地震反应一维时域分析

等效线性化方法在工程中经常被用于土层非线性地震反应一维数值分析,但考虑大震作用将较大峰值加速度时程作为输入时,该方法会引起过大的"共振"效应,造成对地表地震反应的误估。为了更合理的估计非线性地震反应,提出了一种考虑拟合阻尼比、刚度比试验曲线的时域分析方法,并用于响嘡台阵场地土层地震一维非线性反应分析,通过数值模拟结果与实际记录的比较,验证了该方法的可行性。最后,通过数值模拟证明该方法对大震情况下对地表地震反应的估计比等效线性化方法更为合理。

三五阶非线性光纤中光脉冲的啁啾和频谱

为了探讨光纤的五阶非线性对光脉冲传输的影响,利用同时考虑三阶和五阶非线性效应的非线性薛定谔方程,在忽略光纤色散的情况下,解析并计算研究了超高斯光脉冲的非线性相移、频率啁啾。数值模拟了光脉冲传输的功率频谱。结果表明,与只有三阶非线性折射率的情形相比,正五阶非线性折射率的存在使光脉冲在光纤中传输的非线性相移和最大频率啁啾增大,使无啁啾光脉冲的频谱宽度变宽,谱峰数目增多,高斯脉冲初始啁啾对频谱的影响与三阶非线性折射率的情形类似;负五阶非线性折射率则使光脉冲传输的非线性相移和频率啁啾呈现新的特点,并使无啁啾光脉冲的频谱宽度变窄,谱峰数目减少。

螺旋共轭化合物的结构光谱和二阶非线性光学性质的理论研究

用ＡＭ１和ＩＮＤＯ／ＣＩ方法研究了螺旋共轭化合物（ｎ＝１～５）的结构和电子光谱，并在此基础上，用完全态求和公式（ＳＯＳ）自编程序计算了二阶非线性光学系数，从理论上研究了１。