准一维无序系统的电子结构

利用负本征值理论的态密度计算方法，研究了准一维双链无序系统的电子结构。并针对系统大小，对角和非对角无序程等各种参数，探讨了电子的局域化，系统能量分布范围等问题。在引进无序参量后，对角无序主要引起电子局域态的增多，而非对角无序则使系统的能量分布范围发生变化。     

准一维三平行链无序系统电子结构

利用负本征值理论计算方法,重点计算出准一维平行三链无序系统的电子态密度,对比研究了一维单链、准一维双链的情况.在对角无序、非对角无序条件下,具体探讨了电子结构、局域化形成、系统能量分布及维数效应等问题.研究表明,对角无序主要引起电子局域态的增多,非对角无序则使系统的能量分布范围发生变化;通过对一维到带状系统电子结构变化的研究,观察到在相同条件下,从一维到带状系统,电子态密度的峰值数目在增加,而电子态密度为零的能量区间减少,体现出电子能带结构的维数效应.     

光散射聚集速率测定中T矩阵方法的应用

聚集速率是评估胶体体系特性及稳定性的关键参数, 静态光散射和动态光散射则是测量聚集速率的两个重要方法. 然而, 用静态光散射和动态光散射测量聚集速率时, 需要知道有关单粒子和双粒子聚集体光散射特性的数据. 为此, 通常需要把动、静两种方法结合, 才能消去这个数据. 以前各种近似理论曾用来解决这个问题, 但因粒子尺寸和形状的限制, 结果并不理想. 而T矩阵方法可以不受粒子大小和形状的限制计算其光散射特性. 本工作用T矩阵方法直接计算静态光散射和动态光散射所必须的粒子散射特性, 并将该法得到的聚集速率与动静态光散射结合法得到的聚集速率进行了比较, 两者结果很接近. 本工作为简化静态光散射和动态光散射测量聚集速率, 扩展其应用范围开辟了新途径. 关键词： T矩阵')" href="#">T矩阵 光散射法 聚集速率     

O3+与H2碰撞中解离电子俘获过程的全量子计算

利用全量子的分子轨道强耦合方法,我们研究了基态的O3+(2s22p2P)与氢分子碰撞的解离电荷转移过程.分子轨道强耦合计算中采用了自旋耦合价带理论计算的三原子分子势能面和径向耦合矩阵元.对氢分子的自身转动,我们采用无限阶的冲量近似方法.在入射离子能量为0.1 eV/u到500 eV/u的能量区间,我们得到了非解离碰撞过程的振动态选择单电子俘获截面和解离碰撞过程的单电子俘获微分截面,发现解离碰撞截面大约占非解离过程的10%.这表明在实际的应用中,必须包含解离俘获过程的贡献.     

多元可激发气体声弛豫频率的环境影响分析

推导多元可激发气体中声弛豫频率和环境温度、压强的解析关系.理论分析和仿真计算表明：声弛豫频率线性反比于主弛豫过程的弛豫时间,正比于主弛豫过程的振动耦合热容,反比于外自由度热容;温度升高导致振动耦合热容增加、内外自由度能量转移速率增大引起弛豫时间减少,进而造成声弛豫频率正比于环境温度;压强增加使得分子碰撞速率增加引起弛豫时间减少,进而使得声弛豫频率线性正比于环境压强.     

激光作用下薄膜中的电子-声子散射速率

激光功率密度达到太瓦级时，光学激光薄膜破坏中雪崩机制占主导地位. 研究雪崩破坏机理，必然涉及到电子吸收激光能量的速率和电子损耗能量的速率，这些都与电子和声子的散射有密切的联系. 所以，电子受到的散射速率是研究雪崩机制的前提和基础. 本文分析了截断散射声子波矢对散射速率的影响，得到散射速率与电子能量的依赖关系，与其他理论及实验结果一致. 同时还对耦合参数进行了修正，得到了依赖声子波矢的耦合参数，修正结果表明在不改变散射速率与高能电子能量依赖关系的基础上，散射速率整体降低了. 关键词： 激光 薄膜 电子 声子     

电子关联对类铍离子1s~22s2p~3P_(0,1)能级的超精细结构常数的影响

基于MCDF方法系统地计算了Z=20~83范围内24个类铍离子的1s22s2p3P0,1态的精细结构,得到了与其它理论和实验符合很好的结果.在此基础上,进一步计算了超精细结构对角及非对角常数,并分析了不同电子关联效应和Breit相互作用对它们的影响.     

吲哚美辛与牛血清白蛋白结合作用的研究

应用紫外光谱和荧光光谱研究了生理条件下吲哚美辛与牛血清白蛋白的相互作用机理,确定静态猝灭和非辐射能量转移是导致吲哚美辛对BSA荧光猝灭的两大原因。利用荧光猝灭反应求得药物与牛血清白蛋白之间的结合常数和结合位点数,根据热力学参数确定它们之间的作用力类型,依据能量转移理论计算二者相互结合时给体-受体间的距离和能量转移效率,结合紫外吸收光谱和荧光光谱结果, 探讨了吲哚美辛与牛血清白蛋白的相互作用模式。     

自旋轨道耦合量子点系统中的量子相干

研究了自旋轨道耦合量子点中的量子相干效应.运用输运电子的全计数统计方法计算系统的平均电流、散粒噪声和偏斜,发现体系存在自旋轨道耦合作用时,散粒噪声值随自旋轨道耦合常数的增加而减小.更重要的是,电流、噪声和偏斜随磁通周期性波动,并且波动周期不受自旋轨道耦合强度大小、自旋极化率以及动力学耦合不对称的影响.     

可激发气体分子声弛豫过程振动模式能量转移速率计算

研究可激发气体中振动模式能量转移速率和声弛豫过程形成的关系,将单一气体Tanczos弛豫方程理论[J.Chem.Phys.25,439(1956)]扩展应用于混合气体中振动模式的振动-振动(V-V)和振动-平动(V-T)能量转移速率的计算。在室温下CO₂,CH₄,CL₂,N₂和O₂组成的多种混合气体中,振动模式能量转移速率的计算结果表明:对于多个振动模式所形成的声复合弛豫过程,各振动模式的声激发能可由V-V能量转移相互耦合后传递给具有最快V-T转移速率的最低振动频率振动模式,再通过该振动模式的V-T转移退激发形成主弛豫过程。这种选择最快转移路径的声激发量弛豫方式,造成了大多数可激发气体中声弛豫吸收谱的实测数据只存在一个吸收峰的现象。从而提供了一个可通过计算微观振动能量转移速率分析混合气体声弛豫过程形成机理的理论模型。      

Persistence of structure over fluctuations in biological electron-transfer reactions

In the soft-wet environment of biomolecular electron transfer, it is possible that structural fluctuations could wash out medium-specific electronic effects on electron tunneling rates. We show that beyond a transition distance (2-3 A in water and 6-7 A in proteins), fluctuation contributions to the mean-squared donor-to-acceptor tunneling matrix element are likely to dominate over the average matrix element. Even though fluctuations dominate the tunneling mechanism at larger distances, we find that the protein fold is "remembered" by the electronic coupling, and structure remains a key determinant of electron transfer kinetics.     

Electron transfer controlled by conformational variations of a strongly dissipative system

In this paper, there is given a formulation of electron transfer in the system where the conformational transitions are present. The conformation changes were described as classical telegraphic noise. In the work it was assumed that electron transfer reaction can be completely interrupted by the fluctuation of the electronic coupling. A functional-integral formalism to the dynamics of a two-state system was used. The results have been derived within the noninteracting blip approximation with respect to the quantum fluctuations of the heat bath.     

Coherent electronic coupling versus localization in individual molecular dimers

We have investigated electronic excitation transfer in individual molecular dimers by time and spectrally resolved confocal fluorescence microscopy. The single molecule measurements allow for directly probing the distribution of the electronic coupling strengths due to static disorder in the polymer host. We find dimers where the excitation is delocalized (superradiant emission) while for others emission originates from a localized state. Transitions between delocalized and localized states as observed for a given dimer are attributed to structural fluctuations of the guest-host system.     

Spin fluctuations and high temperature superconductivity

Theory of spin fluctuations for itinerant magnetism and its application to high temperature superconductivity are reviewed. After a brief introduction to the whole subject the developments of the self-consistent renormalization theory of spin fluctuations are summarized with particular emphasis on critical properties at the quantum phase transitions. Most of the anomalous properties in the normal state of high-T_c cuprates are understood as due to the critical behaviours for the two dimensional antiferromagnetic metals. By analysing the nuclear magnetic relaxation rate and the T-linear term of resistivity, the set of parameters to specify the spin fluctuations are determined. It is shown that by using the parameters thus obtained one can describe other quantities as well, e.g. optical conductivity. Then we proceed to the theory of superconductivity by the spin fluctuation mechanism. After some discussion on the weak coupling treatments, the strong coupling theory is reviewed. It is shown that the set of parameters determined by the normal state properties of the high-T _c cuprates just give a transition temperature of the right order of magnitude. Among the parameters, the most sensitive one for T _c is the frequency spread of the spin fluctuations. This fact enables us to present a possible unified picture of the antiferromagnetic spin fluctuation-induced superconductors, including heavy fermion superconductors and organic superconductors. This point of view may be confirmed to a certain extent by microscopic calculations based on the fluctuation exchange approximation for the two-dimensional Hubbard models representing not only the cuprates but also organic and trellis lattice compounds. The review is concluded with some discussions on future problems, e.g. the pseudo spin-gap in the under-doped region.     

非平衡涨落问题的微观唯象分析理论(Ⅰ)——一种新的广义不可逆热力学理论与热涨落中涨落—耗散表示式的非平衡修正

本文给出非平衡涨落问题的微观唯象分析理论——非平衡涨落的统计学描述理论。该理论的基础是广义非平衡熵与描述涨落几率的爱因斯坦表示式的推广。通过计算求得刚体热传导中比能与热通量的非平衡涨落的二阶矩。导出对热涨落的通用涨落-耗散表示式的非平衡修正,同时发现该修正相当于固体电介质中的光子热输运与金属中电子热输运的数值修正。     

Self-synchronization of nonlinear oscillations in the presence of fluctuations

A statistical mechanical theory is presented for the self-organization of a macroscopic oscillation with the presence of external fluctuations in a system of Van der Pol oscillators coupled through dissipative interactions. Starting from Langevin equations for the Van der Pol oscillators, the static and dynamic characteristics are studied. The threshold condition is given by the relative size between the fluctuation and the interaction. The transitions between synchronous and asynchronous phases are well discussed by a Landau-type equation. The steady state value of the order parameter and the onset time are compared between the theory and the computer experiments and a good agreement is obtained.     

Relating PAC damping to EFG fluctuation rates through the PAC relaxation peak

A perturbed angular correlation (PAC) experiment that measures dynamic damping also needs information about the fundamental quadrupole frequency to relate the damping as a function of temperature to the EFG fluctuation rate. When the experiment is unable to access slow electric field gradient (EFG) fluctuations that show the fundamental quadrupole frequency directly, one needs additional information to determine the hyperfine field parameters and thereby the connection between observed damping and EFG fluctuation rates. One way to solve this problem is to estimate the hyperfine parameters from the fluctuation rate for maximum damping (i.e. at the relaxation peak) or from the rate of maximum damping. This work relates both the maximum damping rate and the fluctuation rate at the relaxation peak to EFG magnitudes (or quadrupole frequencies) for five dynamic N-state symmetric models of fluctuating EFGs.     

蛋白质构型变化的二维广义郎之万方程描述

采用二维广义郎之万方程描述蛋白质构型的随机变化,并与电子输运过程的原子密度填充模型相协调. 假设通过键和通过空间的两类电子输运路径分别受到高斯分数噪声和高斯白噪声的影响. 推导了电子转移给体-受体距离涨落和荧光寿命涨落自相关函数的一般表达式. 采用数值拉普拉斯反变换计算了蛋白质构型涨落动力学,并详尽讨论了长时间和短时间行为的渐近解析. 最后,明确了基于二维广义郎之万方程的蛋白质构型描述与一维描述之间的关系.     

耗散介观电容耦合电路的量子涨落

给出耗散介观电容耦合电路的量子化,在此基础上研究电荷和电流在能量本征态下的量子涨落,并对其进行讨论 关键词： 耗散电容耦合电路 量子涨落