Ti掺杂NbSe2电子结构的第一性原理研究

采用基于密度泛函理论框架下的第一性原理平面波超软赝势方法, 计算了理想2H-NbSe₂和Ti掺杂2H-NbSe₂晶体的几何结构及电子结构; 对掺杂前后超胞的能带图、态密度及分波态密度图进行了分析. 结果表明, 掺杂后费米能级附近能量区域的电子态密度出现了较高的峰值, 且费米能级位置发生了改变. 理论上可以认为Ti的掺杂会使得NbSe₂的导电性增强, 有利于开发新型的电接触复合材料.     

Second-order Nonlinear Optical Properties of a Series of Azulene Derivatives

The first hyperpolarizabilities of a series of novel azulenic-barbituric acid chromophores have been studied by using 12 excitation wavelengths, ranging from 900 to 1907 nm. The dispersion relation of the first hyperpolarizabilities of chromophores holds the same tendency as the experimental results. In addition, the static first hyperpolarizability β0 of molecules was calculated by means of the Sum-Over-States (SOS) expression and the two-level formula respectively. The results show that these molecules possess large static first hyperpolarizabilities and the, β0 value increases as the donor or acceptor strength enhances; the distorted degree of molecules has also an important influence on the β0 value.     

Second-order Nonlinear Optical Properties of a Series of Benzothiazole Derivatives

The second-order nonlinear optical (NLO) properties of a series of benzothiazole derivatives were studied by use of the ZINDO-SOS method.These chromophores are formed by a donor- π- bridge-acceptor system,based on a nitro group connected with benzothiazole as the acceptor and a hydroxyl-functional amino group as the donor.For the purpose of comparison,we also designed molecules in which nitrobenzene is an acceptor,The calculation results indicate that benzothiazole derivatives exhibit larger second-odrder polarizabilities than nitrobenzene derivatives.In order to clarify the origin of the NLO response of these chromophores,their electron properties were investigated as well.The benzothiazole derivatives are good candidates for application in electro-optical device due to their high optical nonlinearities,good thermal and photonic stability.     

Mn和Fe掺杂SnO2的水热合成与磁结构研究

采用水热法合成了Sn1-x-yMnxFeyO2(0≤x≤0.10, 0≤y≤0.10)稀磁半导体. 通过XRD, Raman, TEM, SQUID和Mössbeaur等技术对化合物进行了结构和性能的表征. 结果表明, XRD中没有出现第二相的沉积, Raman光谱中出现了Mn位于SnO2晶格中的局域模式. 磁性测试结果表明, 当x=0.10, y=0时, 样品在低温下具有较强的磁化强度, 但室温下其磁化强度急剧降低. 而y=0.10, x=0时, 样品的磁化强度和矫顽力都比较小, 但随温度的改变变化不大, Mössbeaur谱测试结果表明, 其中的Fe一部分是铁磁耦合的, 拟合得到超精细场和同质异能移等参数表明, 铁磁性来源于Fe替代SnO2本征性能. Mn和Fe共同掺杂的样品的磁化强度随x的减少和y的增加而减少, 矫顽力却相对于单一元素掺杂的样品大大增加.     

纤锌矿型β-CuGa1-xZnxO2的Zn2+取代Ga3+不等价掺杂对其结构及光催化性质的影响

采用离子交换法制备了Zn²⁺在Ga-位不等价掺杂的功能陶瓷材料（β-CuGa_1-xZn_xO₂）. 通过X射线衍射（XRD）和透射电子显微镜（TEM）对材料的晶体结构进行表征, 通过原位高温X射线衍射（HT-XRD）和同步热分析仪（TG-DSC）对材料的热稳定性进行表征, 通过紫外-可见漫散射光谱（UV-Vis DRS）以及第一性原理计算对材料的光学性质进行研究, 并通过甲基橙（MO）的降解反应评价了Zn²⁺在Ga-位的引入对该功能陶瓷光催化性能的影响. 结果显示, Zn²⁺的引入引起带隙变宽, 吸光范围变窄, 自发极化变小, 进而导致单位时间内生成的高活性物质减少, 不利于降解反应. 通过光致发光光谱（PL）对降解机理进行了初步探究. 根据实验结果提出了改进β-CuGaO₂性质的可能方法.     

A Relative Study on Two-photon Absorption Properties of C60 and C70

We have theoretically investigated the one- and two-photon absorption properties of C60 and C70 using the ZINDO method. From the results it is suggested that the one-photon absorption spectra are in agreement with the experimental observations. It is found that the maximum TPA cross section of C70 is more than twice that of C60,which is consistent with the experimental results. A notable point is that the TPA process of C60 is different from that of C70 as well as other ordinary conjugated molecules.     

含三种不同π电子中心的几种双光子吸收材料的理论研究

用密度泛函理论及ZINDO方法,从理论上研究了含二苯乙炔、二苯乙烯和偶氮苯等3种不同π电子中心的几种非线性光学(NLO)材料的双光子吸收截面δ(ω)及三阶非线性光学系数(γ).同时以正确的分子几何构型及UV-Vis光谱为基础,系统地研究和对比了它们的单光子吸收(OPA)和双光子吸收(TPA)的吸收峰位置.     

Calculations on the Nonlinear Second—Order Optical Polarizabilities for Series of Donor—C60 Molecules

IntroductionThebulkpreparation1ofC6 0 andC70 clusters(fullerenes)hasstimulatedawidevarietyofexperimentalandtheoreticalstudies .2 5Wehavesuccessfullyexaminedthestructures ,UV visiblespectraandthenonlinearthird orderopticalpolarizabilities (γ)ofC6 0 andC70 .6 ,7Byin troductionofsubstituents ,thecentrosymmetriesofC6 0 andC70 arebrokenandthesecond orderopticalnonlinearitiesareinduced .ThechargeseparationinsubstitutedC6 0whichleadstoenhancementofβvaluehasalsobeendis cussed .5Inrecentyears ,a…     

含1,3-二硫-2叶立德烯的系列有机发色团的二阶非线性光学性质的理论研究

设计了12个含有1,3-二硫-2叶立德烯的具有二阶非线性光学性质的有机发色团,对所研究分子用AM1方法进行几何构型优化,用INDO/CI方法获得基态到各激发态的垂直跃迁能和振子强度,即电子光谱;在此基础上用SOS公式计算系列分子的二阶非线性光学系数β_ijk,并从微观上对这一系列分子进行比较,为进一步探索综合性能较好的NLO有机物提供了理论指导.     

LaPbMnSbO6化合物的结构精修和磁性表征

采用半化学两步法合成了双钙钛矿氧化物LaPbMnSbO₆,研究了其晶体结构和磁学性质。 通过对XRD谱图进行Rietveld结构精修可以得到,该化合物为单斜晶系的P2₁/n(No.14)空间群,B位MnO₆和SbO₆八面体为岩盐有序结构。 由于A位Pb²⁺离子的存在而产生二级Jahn-Teller效应,使得B位八面体内部晶格畸变具有各向异性。磁性测试表明该样品呈典型的反铁磁有序特征,反铁磁转变温度T_N=9 K。