稀土元素Sm与C共掺SnO2的电子结构和光学性质的第一性原理研究

利用第一性原理密度泛函理论,计算了Sm-C共掺SnO2体系的能带结构、能态密度、光学性质.计算结果表明:Sm-C近邻共掺体系的晶胞的结构比较稳定.在电子结构方面,共掺体系的禁带宽度值最小,表明电子从价带激发到导带所需的能量最小.在光学性质方面,掺杂体系都发生了红移,其中Sm-C共掺体系的红移程度最大,增强了对可见光的响应范围;在可见光区,掺杂体系的反射系数、静态介电常数、静态折射率的值都大于纯SnO2,且Sm-C共掺杂体系的值最大.     

从一道习题的疏误谈起

指出某教材及其配套习题集中一道习题的疏误之处,强调在讨论线性空间中某些问题时,一定要注意数域P的重要性.     

线性互补问题模系多重网格方法的AMSOR光滑算子

为了改进求解大型稀疏线性互补问题模系多重网格方法的收敛速度和计算时间,本文采用加速模系超松弛(AMSOR)迭代方法作为光滑算子.局部傅里叶分析和数值结果表明此光滑算子能有效地改进模系多重网格方法的收敛因子、迭代次数和计算时间.     

Solving the initial condition of the string relaxation equation of the string model for glass transition:part-Ⅱ

The string model for the glass transition can quantitatively describe the universal α-relaxation in glassformers. The string relaxation equation (SRE) of the model simplifies the well-known Debye and Rouse--Zimm relaxation equations at high and low enough temperatures, respectively. However, its initial condition, necessary to the further model predictions of glassy dynamics, has not been solved. In this paper, the general initial condition of the SRE for stochastically spatially configurative strings is solved exactly based on the obtained special initial condition of the SRE for straight strings in a previous paper (J. L. Zhang et al. 2010 Chin. Phys. B 19, 056403).     

Simulations of the flipping images and microparameters of molecular orientations in liquids according to molecule string model

The relaxation dynamics of liquids is one of the fundamental problems in liquid physics, and it is also one of the key issues to understand the glass transition mechanism. It will undoubtedly give enlightenments on understanding and calculating the relaxation dynamics if the molecular orientation flipping images and relevant microparameters of liquids are studied. In this paper, we first give five microparameters to describe the individual molecular string (MS) relaxation based on the dynamical Hamiltonian of the MS model, and then simulate the images of individual MS ensemble, at the same time calculate the parameters of the equilibrium state. The results show that the main molecular orientation flipping image in liquids (including supercooled liquid) is similar to the random walk. In addition, two pairs of the parameters are equal, and one can be ignored compared with the other. This conclusion will effectively reduce the difficulties in calculating the individual MS relaxation based on the single-molecule orientation flipping rate of general Glauber type, and the computer simulation time of interaction MS relaxation. Moreover, the conclusion has no doubt of the reference significance for solving and simulating the multi-state MS model.     

New smooth gap function for box constrained variational inequalities

A new smooth gap function for the box constrained variational inequality problem(VIP) is proposed based on an integral global optimality condition.The smooth gap function is simple and has some good differentiable properties.The box constrained VIP can be reformulated as a differentiable optimization problem by the proposed smooth gap function.The conditions,under which any stationary point of the optimization problem is the solution to the box constrained VIP,are discussed.A simple frictional contact problem is analyzed to show the applications of the smooth gap function.Finally,the numerical experiments confirm the good theoretical properties of the method.     

应急物资政企联合储备合作机理研究

针对一些应急物资,采用政府企业联合储备方式储备,可以降低政府储备成本,企业也可以从中获益。本文研究政企联合实物储备的合作机理,分析了联盟参与人之间的博弈关系,建立了联盟收益模型,运用shapley值解决合作的联盟收益分配问题,最后分析了联盟的稳定性。算例分析显示在政企合作联盟中政府和企业关系类似“地主”和“农民”的关系,当企业获得的收益小于其机会成本时,企业不愿意加入联盟,这时政府需对企业进行交叉补贴来维持联盟稳定。缺货成本低于政府储备成本时,政府会考虑与企业联合储备或者选择缺货;缺货成本低于企业储备成本时,政府选择缺货。     

Dynamic behaviors of water contained in calcium-silicate-hydrate gel at different temperatures studied by quasi-elastic neutron scattering spectroscopy

The dynamic behaviors of water contained in calcium-silicate-hydrate(C-S-H) gel with different water content values from 10%to 30%(by weight),are studied by using an empirical diffusion model(EDM) to analyze the experimental data of quasi-elastic neutron scattering(QENS) spectra at measured temperatures ranging from 230 K to 280 K.In the study,the experimental QENS spectra with the whole Q-range are considered.Several important parameters including the bound/immobile water elastic coefficient A,the bound water index BWI,the Lorentzian with a half-width at half-maximum(HWHM) Γ_1(Q) and Γ_2(Q),the self-diffusion coefficients D_(t1) and D_(t2) of water molecules,the average residence times τ_(01)and τ_(02),and the proton mean squared displacement(MSD)(u~2) are obtained.The results show that the QENS spectra can be fitted very well not only for small Q(≤1 A~1) but also for large Q.The bound/immobile water fraction in a C-S-H gel sample can be shown by the fitted BWI.The distinction between bound/immobile and mobile water,which includes confined water and ultra-confined water,can be seen by the fitted MSD.All the MSD tend to be the smallest value below 0.25 A~2(the MSD of bound/immobile water) as the Q increases to 1.9 A~1 no matter what the temperature and water content are.Furthermore,by the abrupt changes of the fitted values of D_(t1),τ_(01),and Γ_1(Q),a crossover temperature at 250 K,namely the liquid-to-crystal-like transition temperature,can be identified for confined water in large gel pores(LGPs) and/or small gel pores(SGPs) contained in the C-S-H gel sample with 30% water content.     

Zn1-x HfxO的电子结构和光学性质的第一性原理计算

基于第一性原理密度泛函理论,计算分析了Zn1-xHfxO(x=0,0.0312,0.0417,0.0625和0.1250)体系的晶格结构、电子结构,Mulliken电荷布居和光学性质.计算结果表明,随着Hf掺杂摩尔百分比的增大,晶体体积膨胀,费米能级进入导带,其附近的导带部分主要由杂质原子Hf的5d态贡献,Hf-O离子键成分作用凸显,故Hf的掺杂引入施主能级进而形成n型ZnO材料的可能性较大.且通过比较吸收谱、反射谱和折射谱,发现适量掺入Hf原子可使ZnO体系在高能区的透过率增加,能量损失谱出现红移.这些性质均与实验中Hf掺杂有类似结果,由此可知适量掺杂Hf的ZnO体系有望在制备光电子器件等领域发挥作用.     

晶面选择性生长对球形氢氧化镍形貌及电化学活性的影响

在相同的物理化学条件、不同晶化时间的条件下,采用化学沉淀法制备球形氢氧化镍晶体并应用SEM技术分别考察制得样品的形貌。研究表明：在相同的物理化学条件下,随着晶化时间的增加,样品的微观形貌由不规则状晶体变为完整的球状晶体。结合XRD表征结果分析得出：（001）晶面在晶化时间达到3 h时生长到了一个稳定的状态,并不随着晶化时间的增加而有明显的变化,但（100）与（101）晶面随晶化时间的增加继续生长,当晶化时间达到12 h时氢氧化镍的相对结晶度最大,（100）与（101）衍射峰强度高且峰形尖锐,说明氢氧化镍晶体的结构规整性增强。本文还讨论了氢氧化镍生长结晶过程中晶面选择性生长对晶体形貌及电化学性能的影响。