基于波动光学的虹与霓最佳观测角的理论研究

虹与霓的最佳观测角是观测到虹与霓现象最明显的观测角.已有的研究表明,虹与霓观测角对入射角的极值就是最佳观测角.根据波动光学原理,分析了任意入射角下产生虹或霓的光束进入眼睛的光能量流的大小,并计算得到了在观测角的极值位置时光能量流最大,从而验证了上述结论,并在此基础上做了简要分析.     

链间耦合对极化子非弹性散射性质的影响

基于一维紧束缚的Su-Schreiffer-Heeger模型, 采用非绝热动力学方法, 研究了链间耦合对聚合物中极化子对非弹性散射性质的影响: 激子的产生依赖于链间耦合, 随着耦合强度的增加, 正负极化子对的电子波函数交叠增强, 利于提高激子的产率; 当耦合区域是极化子的宽度时, 正负极化子对波函数的耦合最充分、耦合最强, 电荷跃迁更容易, 激子产率最大. 关键词： 聚合物 极化子 激子     

The effect of interface hopping on inelastic scattering of oppositely charged polarons in polymers

The inelastic scattering of oppositely charge polarons in polymer heterojunctions is believed to be of fundamental importance for the light-emitting and transport properties of conjugated polymers. Based on the tight-binding SSH model, and by using a nonadiabatic molecular dynamic method, we investigate the effects of interface hopping on inelastic scattering of oppositely charged polarons in a polymer heterojunction. It is found that the scattering processes of the charge and lattice defect depend sensitively on the hopping integrals at the polymer/polymer interface when the interface potential barrier and applied electric field strength are constant. In particular, at an intermediate electric field, when the interface hopping integral of the polymer/polymer heterojunction material is increased beyond a critical value, two polarons can combine to become a lattice deformation in one of the two polymer chains, with the electron and the hole bound together, i.e., a self-trapped polaron-exciton. The yield of excitons then increases to a peak value. These results show that interface hopping is of fundamental importance and facilitates the formation of polaron-excitons.     

Variational Calculations of Neutral Bound Excitons in GaAs Quantum-Well Wires

The binding energy of an exciton bound to a neutral donor (D^0, X) in GaAs quantum-well wires is calculated variationally as a function of the wire width for different positions of the impurity inside the wire by using a two-parameter wavefunction. There is no artificial parameter added in our calculation. The results we have obtained show that the binding energies are closely correlated to the sizes of the wire, the impurity position, and also that their magnitudes are greater than those in the two-dimensional quantum wells compared. In addition, we also calculate the average interparticle distance as a function of the wire width. The results are discussed in detail.     

讲好量子力学绪论课从Planck公式推证开始

从量子力学绪论课的开端——黑体辐射入手,在普朗克能量量子化假说,引入普朗克常数基础上,结合完善的热力学统计物理学理论,对Planck辐射公式进行了简单、清晰的推证.拨开迷雾,从源头开始,阐明Planck辐射定律及其物理背景,使学生明白量子论的产生不是凭空的,是解决经典物理学中所存在的矛盾的必然性结果,从而能够帮助学生更好地理解量子力学,使得量子力学及相关课程教学效果得到很好的提升.     

Effects of polarons on static order hyperpolarizabilities polarizabilities and second of conjugated polymers

According to the one-dimensional tight-binding Su-Schrieffer-Heeger model, we have investigated the effects of charged polarons on the static polarizability, axx, and the second order hyperpolarizabilities, γxxxx, of conjugated polymers. Our results are consistent qualitatively with previous ab initio and semi-empirical calculations. The origin of the universal growth is discussed using a local-view formalism that is based on the local atomic charge derivatives. Furthermore, combining the Su Schrieffer-Heeger model and the extended Hubbard model, we have investigated systematically the effects of electron-electron interactions on αxx and γxxxx of charged polymer chains. For a fixed value of the nearest-neighbour interaction V, the values of αxx and γxxxx increase as the on-site Coulomb interaction U increases for U 〈 Uc and decrease with U for U 〉 Uc, where Uc is a critical value of U at which the static polarizability or the second order hypcrpolarizability reaches a maximal value of αxx or γxxxx. It is found that the effect of the e-e interaction on the value of αxx is dependent on the ratio between U and V for either a short or a long charged polymer. Whereas, that effect on the value of γxxxx is sensitive both to the ratio of U to V and to the size of the molecule.     

Dynamics of Polaron at Polymer/Polymer Interface

The migration of a polaron at polymer/polymer interface is believed to be of fundamental importance for the transport and light-emitting properties of conjugated polymer-based light emitting diodes. Based on the one- dimensional tight-binding Su-Schrieffer-Heeger （SSH） model, we have investigated polaron dynamics in a one- dimensional polymer/polymer system by using a nonadiabatic evolution method. In particular, we focus on how a polaron migrates through the conjugated polymer/polymer interface in the presence of external electric field. The results show that the migration of polaron at the interface depends sensitively on the hopping integrals, the potential barrier induced by the energy mismatch, and the strength of applied electric field which increases the polaron kinetic energy.     

电子-晶格耦合非线性项对极化子性质的影响

基于一维紧束缚SSH模型,讨论了电子晶格耦合二阶项对极化子静态和动力学性质的影响：随着二阶项系数β的增加,二聚化常数越来越大,能隙越来越宽,极化子的局域性不断增强,但带宽几乎没有变化.动力学方面由于二阶项的引入增强了电声相互作用,随着β值的增大,极化子的运动速度减小,并且极化子的解离电场不断增大. 关键词： SSH模型 电-声耦合二阶项 极化子     

Effects of polarons on static polarizabilities and second order hyperpolarizabilities of conjugated polymers

According to the one-dimensional tight-binding Su-Schrieffer-Heeger model,we have investigated the effects of charged polarons on the static polarizability,α xx,and the second order hyperpolarizabilities,γ xxxx,of conjugated polymers.Our results are consistent qualitatively with previous ab initio and semi-empirical calculations.The origin of the universal growth is discussed using a local-view formalism that is based on the local atomic charge derivatives.Furthermore,combining the Su-Schrieffer-Heeger model and the extended Hubbard model,we have investigated systematically the effects of electron-electron interactions on α xx and γ xxxx of charged polymer chains.For a fixed value of the nearest-neighbour interaction V,the values of α xx and γ xxxx increase as the on-site Coulomb interaction U increases for U U c and decrease with U for U U c,where U c is a critical value of U at which the static polarizability or the second order hyperpolarizability reaches a maximal value of α max or γ max.It is found that the effect of the e-e interaction on the value of α xx is dependent on the ratio between U and V for either a short or a long charged polymer.Whereas,that effect on the value of γ xxxx is sensitive both to the ratio of U to V and to the size of the molecule.     

杂质离子对有机共轭聚合物中极化子动力学性质的影响

基于一维紧束缚Su-Schrieffer-Heeger模型, 采用分子动力学方法, 讨论了杂质势的强度和杂质之间的距离对电子和空穴极化子动力学性质的影响. 研究结果表明: 1)当杂质势强度保持不变时, 两杂质离子之间的距离(d)在2-16个晶格常数变化时, 电子极化子的平均速度大于空穴极化子的平均速度, 这是由于电子、空穴极化子与杂质势的库仑作用不同而产生的差异, 同时极化子的平均速度随d的增加而增大; 若继续增加杂质离子之间的距离, 电子和空穴极化子的平均速度几乎保持不变, 仅有一些微小的振荡, 这是由于不同距离的杂质离子对电子和空穴极化子产生的势垒或势阱的叠加效果不同而引起的; 2)保持两杂质离子之间的距离不变时, 随着杂质势强度的增大, 电子和空穴极化子的平均速度均减小, 且空穴极化子的平均速度减小趋势更明显.