快离子导体系统中Li+运动的7Li NMR研究

Lil＋2。TiZ。Mg。P3012是一种具有较高离子导电车的快离子导体材料，其结晶化学和电导性能都已经进行了深入的研究，表明化合物具有规整的三维骨架结构，h离子位于骨架间隙中，并且其离子电导率随温度升高而增加＊．作者曾应用”P固体高分辨NMR技术对该固港体系统的微观晶体结构进行了研究，分析了Mg’“离子部分替代Ti‘“离子后，化合物骨架结构的特征＊．但对该体系的Li离子微观动态行为的研究还没有开展，在这里我们应用、i固体NMR技术研究了L计的状态及其动态行为，在此基J由上分析了Li离子可能的迁移机理．1实验部分’LiNMR…     

Direct current conductivity and ion motions in poly(vinyl chloride)‐poly‐1,4‐cis butadiene blends by electrical relaxation method

Ionic conduction in poly(vinyl chloride) (PVC)‐poly‐1,4‐cis butadiene blends has been studied using the electrical relaxation method. Temperature dependence of direct current (dc) conductivity does not change at the glass transition of PVC but does change at higher temperatures. The shape of the frequency dispersion curve of the electric modulus in a frequency range from 0.01 to 100 Hz depends on temperature. At low temperatures, the shape of the dispersion curve is reproduced by calculation assuming the Debye decay function, whereas this is not reproduced at high temperatures. Two kinds of analysis of the dispersion curve are discussed for this complicated change in the shape of the dispersion. One is that the dispersion curve is regarded as a single process expressed by the Kohlrausch decay function, and the other is that the curve is regarded as two processes expressed by the Debye and the Kohlrausch decay functions. The observed dispersion of the electric modulus is not expressed by the single process but by the two processes. One of the two processes is characterized by the Debye decay function, and the other is characterized by the Kohlrausch decay function. The parameter of the Kohlrausch decay function for one of these processes has a value of 0.82, and this value does not depend on temperature. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 226–235, 2002     

含环氧基聚二甲基硅氧烷及其硫化过程的分子运动

采用扭辩分析法详细研究了含环氧基聚二甲基硅氧烷在１１０－２３０Ｋ范围内的的分子运动情况，讨论了氧基团对聚二甲基硅氧烷主链的玻璃化转变温度，次级转变温度、烷融温度及粘流浊国度等动态力学性能的影响。     

Exactly Solvable Model Mimicking the H<Subscript>2</Subscript> Molecule in the Limit of Large Nuclear Masses

Avoiding the limitations of the Born–Oppenheimer approximation remains an issue of continuing importance in molecular physics. If we take the H₂ molecule as a prototype, then one uses, in some sense, the ratio of electron mass m to nuclear mass M as an expansion parameter, sometimes cited to be explicitly (m/M)^1/4. Here, we employ a model of such a two-electron diatomic molecule set up by Makarewicz [Am. J. Phys. 54 (1986) 178] to study the exact ground-state wave function obtained by treating electrons and nuclei on the same footing, Of course, to obtain such a wave function analytically means adopting model force laws, both for confinement and for the interelectronic interaction. From the exact wave function and ground-state energy, contact is finally established with the large nuclear mass limit.     

An explicit calculation of the mean of the perimeter of the convex hull of a plane random walk

If (X _n ) _n ⁼¹ is a sequence of i.i.d. random variables in the Euclidean plane such that we compute the mean of the perimeter of theconvex hull ofX ₁++X _k; 0kn}.     

Lyapunov function for the Kuramoto model of nonlinearly coupled oscillators

A Lyapunov function for the phase-locked state of the Kuramoto model of non-linearly coupled oscillators is presented. It is also valid for finite-range interactions and allows the introduction of thermodynamic formalism such as ground states and universality classes. For the Kuramoto model, a minimum of the Lyapunov function corresponds to a ground state of a system with frustration: the interaction between the oscillators,XY spins, is ferromagnetic, whereas the random frequencies induce random fields which try to break the ferromagnetic order, i.e., global phase locking. The ensuing arguments imply asymptotic stability of the phase-locked state (up to degeneracy) and hold for any probability distribution of the frequencies. Special attention is given to discrete distribution functions. We argue that in this case a perfect locking on each of the sublattices which correspond to the frequencies results, but that a partial locking of some but not all sublattices is not to be expected. The order parameter of the phase-locked state is shown to have a strictly positive lower bound (r 1/2), so that a continuous transition to a nonlocked state with vanishing order parameter is to be excluded.     

The motion of a tagged particle and nonhomogeneous media in R1

We analyze the asymptotic behavior of a tagged particle inside an infinite system of identical elastic point masses. The main objective is to study very nonhomogeneous media—particles which are more and more dispersed far from the origin. We suggest that the limit motion of a tagged particle may serve to classify media in the nonhomogeneous case as well as in the homogeneous case.     

Connected Triple Excitations in the Calculation of the Adiabatic Excitation Energies in the Equation-of-Motion Coupled Cluster Theory

The importance of the connected triple excitations (T ₃ operator) in the calculations of the adiabatic excitation energies are estimated for two diatomic closed shell molecules: N₂ and CO. The computations are carried out using the recently developed equation-of-motion (EOM) approach with full inclusion of the connected triple excitations [Kucharski, S. A., Woch, M., Musia, M., Bartlett, R. J. J. Chem. Phys. 2001, 115, 8263.] The effect of the T ₃ operator on the calculated excitation energies ranges from 0.1 to 0.3 eV significantly improving the results for all considered states. In all but one case the agreement with the experimental data is better than 0.05 eV.     

用耦合簇运动方程计算分子的多光子吸收截面

简短评述了多光子吸收过程的原理与应用．由于该过程的高度非线性，对于分子的高激发态性质的描述要求很高，因为从本质上讲，这涉及到从低激发态到高激发态的跃迁过程．我们提出了用耦合簇运动方程方法并结合半经验哈密顿参数来计算大分子体系的多光子吸收截面．以蒽一卟啉一蒽分子为例，从激发态之间的跃迁密度分析发现，分子内电荷转移过程可以极大地增强三光子吸收．     

Solution of the Fokker-Planck equation for the shock wave problem

An eigenexpansion solution of the time-independent Brownian motion Fokker-Planck equation is given for a situation in which the external acceleration is a step function. The solution describes the heavy-species velocity distribution function in a binary mixture undergoing a shock wave, in the limit of high dilution of the heavy species and negligible width of the light-gas internal shock. The diffusion solution is part of the eigenexpansion. The coefficients of the series of eigenfunctions are obtained analytically with transcendentally small errors of order exp(–1/M), whereM 1 is the mass ratio. Comparison is made with results from a hypersonic approximation.