氢键分子系统中外场与阻尼作用下扭结孤子对的特性研究

运用二分量孤子的振子模型，研究了氢键分子系统中在外场与阻尼存在情况下，质子子晶格与重离子子晶格中扭结孤子形成的孤子对的运动特性，讨论了重离子运动对孤子对迁移率的影响和孤子对的核化特性，得到了孤子对迁移率表达式和平均核化率     

一维分子链中激子与声子的相互作用和呼吸子解

运用连续极限近似，求解声子与激子相互作用的运动方程，得到了简谐分子链和 非简谐分子链中晶格振动的孤子解，在考虑三次非简谐势的情况下，一维分子链晶格振动具 有扭结孤子解，在考虑具有四次非简谐势的情况下，得到一维分子链晶格振动具有呼吸子解 . 关键词： 一维分子链 激子 声子 孤子 呼吸子 非线性效应     

氢键分子系统的非线性激发和质子传递的理论

基于对氢键分子系统中质子激发和移动的特点的仔细分析，提出一个新的哈密顿函数和理论，用以研究由质子位移所导致的质子的局域性涨落和重离子子晶格的构象畸变而引起的质子的集体激发和质子传递的特性，给出了运动方程和相应的孤立子解，讨论了这些解的特征 关键词：     

氢键分子系统的非线性激发和质子的传导特性

我们首先介绍了氢键系统的特性和质子在此系统中的运动特点及国际上对此问题研究的进展和存在的问题。接着较全面地描述我们提出的新理论的物理学基础、模型的特征和所形成的两类缺陷和质子孤子的特性。这个模型的最大特点是存在两类不同性质的非线性相互作用 ,它们之间的竞争和平衡导致了两类不同的缺陷和相应孤子的出现 ,这两类缺陷的协同和交替运动使质子在氢键系统中从一处传递到另一处。因此 ,此模型能完整地解释质子在氢键系统中的传递 ,在此基础上我们研究了重离子作非简谐振动和系统中存在的杂质及氢离子的迁移所产生的偶极矩等效应对质子孤子的影响以及在外场存在时 ,质子运动的特点 ,求出了质子在电场作用下的迁移率和传导率、大约分别为 (6 5 - 6 .9)× 1 0 - 6(m2 /v .s)和(7.6 - 8.1 )× 1 0 - 3/(Ωm) ,它刚好处在半导体范围内 ,与实验结果基本吻合。并且我们研究了质子传递的量子力学特性和质子孤子存在的临界温度     

氢键分子系统的非线性激发和质子的传导特性

我们首先介绍了氢键系统的特性和质子在此系统中的运动特点及国际上对此问题研究的进展和存在的问题。接着较全面地描述我们提出的新理论的物理学基础、模型的特征和所形成的两类缺陷和质子孤子的特性。这个模型的最大特点是存在两类不同性质的非线性相互作用 ,它们之间的竞争和平衡导致了两类不同的缺陷和相应孤子的出现 ,这两类缺陷的协同和交替运动使质子在氢键系统中从一处传递到另一处。因此 ,此模型能完整地解释质子在氢键系统中的传递 ,在此基础上我们研究了重离子作非简谐振动和系统中存在的杂质及氢离子的迁移所产生的偶极矩等效应对质子孤子的影响以及在外场存在时 ,质子运动的特点 ,求出了质子在电场作用下的迁移率和传导率、大约分别为 (6 5 - 6 .9)× 1 0 - 6(m2 /v .s)和(7.6 - 8.1 )× 1 0 - 3/(Ωm) ,它刚好处在半导体范围内 ,与实验结果基本吻合。并且我们研究了质子传递的量子力学特性和质子孤子存在的临界温度     

光晶格势阱中二元凝聚体的矢量孤子的振荡和分裂

考虑外部囚禁势阱为光晶格势阱,研究了二元玻色-爱因斯坦凝聚体中亮-亮孤子的动力学行为.结果表明,亮-亮孤子的运动方向和振荡行为可以分别通过调节光晶格势阱的晶格常数和势阱深度来控制.进一步地,亮-亮孤子还可以被局域在光晶格势阱中,并且随着势阱深度的增加,局域孤子会产生分裂行为.     

共轭高分子链中电荷迁移的热效应

从理论上研究了共轭高聚物链中在电场作用下极化子运动的热效应.基于SSH模型以及通过绝热动力学演化的方法,模拟了共轭高聚物链中极化子在电场作用下从链左端向右端运动的过程.晶格受到的热扰动作用假设为通过局域的晶格范围内原子位移的随机涨落来实现.结果发现,晶格中的局域热涨落对于运动中的极化子而言等效于一个势垒.势垒高度由高分子中受到热扰动的区域的范围大小以及该区域与其周围环境的温差来决定.当分子中存在热吸收不均匀的现象时,链内极化子迁移率在低电场范围内随电场的变化遵循对数曲线变化规律.     

用非线性薛定谔方程讨论超晶格中畴的运动

用非线性薛定谔方程讨论超晶格畴的形成和漂移,得到具有负微分电导特性的超晶格中畴的波函数是Bloch函数的一个孤子型包络函数,它在外电场作用下做漂移运动. 关键词：     

孤立子及其相互作用的初等分析

用较简捷而直观的试探解法几种典型的孤立子方程（ＫｄＶ方程，Ｔｏｄａ晶格波方程，ＳＧ方程与ＮＬＳ方程）求得单孤子解和两孤子解，以说明孤子及孤立子间相互作用的特点，并讨论了物理意义。     

分数阶衍射蜂窝晶格中带隙涡旋孤子的传输与控制

基于分数阶非线性薛定谔方程,研究分数阶衍射效应下蜂窝晶格中带隙涡旋光孤子的存在性与传输特性.首先采用平面波展开法得到蜂窝晶格能带结构,其次在带隙结构中分别采用改进的平方算子迭代法、分步傅里叶法和傅里叶配置法研究含有蜂窝晶格势的分数阶非线性薛定谔方程中带隙涡旋孤子的模式及其传输特性.研究结果发现带隙涡旋孤子的传输特性受Iévy指数和传播常数的影响.在稳定区间,带隙涡旋孤子可以稳定传输,而在非稳定区间,带隙涡旋孤子会随着传输距离的增加而逐渐汇聚,失去环状结构演变为基孤子.且Lévy指数越大,带隙涡旋孤子能够稳定传输的距离越长,功率越低.此外,相邻晶格同相位两个带隙涡旋孤子与旁瓣能量相叠加,反相位两带隙涡旋孤子与旁瓣能量相抵消,传输过程中逐渐失去环状结构,演化为类偶极子模式,且受方位角调制影响而周期性旋转.在非相邻晶格处两带隙涡旋孤子,由于旁瓣影响较小,带隙涡旋孤子在传输过程中能较好地保持环状结构.     

Proton Transport in Hydrogen-Bonded Chains in the Presence of an External Field

The motion of a kink pair consisting of kink soliton in different sublattices in hydrogen-bonded chains in the presence of an external force and damping is discussed based on a new soliton model. The scattering cross-section of a kink pair for an electromagnetic wave and the mobility of a kink pair are found.     

Statistical description of the shape of a moving dislocation

The shape and mobility of dislocations gliding (climbing) over the crystal relief are studied. The mobility of a dislocation is governed by the probability of critical nucleation on it of various defects (the formation of a double kink or break-away from a barrier during sliding, the formation of a jog during absorption (emission) of an interstitial (vacancy) during climbing, etc.). It is demonstrated that the transitional and steady-state modes of dislocation motion exist (the transitional and steady-state modes of deformation). The time required to achieve the steady-state dislocation motion and the velocity of this motion in the absence and in the presence of various types of pinning (drag) centers are calculated. The pinning centers qualitatively change the steady-state velocity of dislocations and increase the time required to reach this mode of motion.     

Role of defects in the kink mechanism of state switching

State switching occurring via the kink mechanism in linear systems has been described considering the effect of defects forming centers of enhanced kink pair nucleation and obstacles for kink propagation. An equation describing the switching kinetics has been derived considering the stochastic nature of kink pair formation in time and the random distribution of defects in space. Using this equation, the average switching time has been calculated as a function of the defect density and delay times caused by defects, and the ranges of parameters with domination of this or that defect type have been determined. The theory has been applicable to magnetic nanowires, dislocations, biological macromolecules, and many other systems.     

Nonlinear Excitations in Hydrogen-Bonded Chains with Anharmonic Interatomic Interactions

We discuss the nonlinear excitations and the motion of a kink soliton pair in hydrogen-bonded chains with anharmonic interatomic interactions, based on a two-component soliton model, using a direct perturbation method. The expression for the asymmetric solutions of the kink soliton pair is found because of anharmonicity, and the energy, the momentum and the effective mass of a kink pair for cubic and quartic anharmonicity are calculated, which are in good agreement with the experimental data.     

Recombination-induced stacking faults: evidence for a general mechanism in hexagonal SiC

We report on optically induced nucleation and expansion of stacking faults in hexagonal SiC structures. The activation energy for partial dislocation glide under optical excitation is found to reduce to 0.25 +/- 0.05 eV, which is about 2 eV lower than for pure thermal activation. From the measurements of thermal activation and below-gap excitation spectroscopy of dislocation glide, we conclude that the elementary process controlling expansion of stacking faults is kink pair nucleation aided by the phonon-kick mechanism. We propose that solitons on 30 degrees Si(g) partials with a silicon core act as deep 2.4 eV + Ev trap sites, readily providing electron-hole recombination energy to enhance the motion of dislocations. Our results suggest that this is a general mechanism of structural degradation in hexagonal SiC.     

Motion of Kink in Hydrogen-Bonded Chain with Asymmetric Double-Well Potential

We discuss the nonlinear excitations and the motion of kink in hydrogen-bonded chain with asymmetric double-well potential, in presence of an external force and damping using a new two-component soliton model. We obtain the kink soliton solution using the phase-plane method, we study soliton velocity and find the expression of the mobility of the kink soliton.     

Activated dynamics of semiflexible polymers on structured substrates

We study the thermally activated motion of semiflexible polymers in double-well potentials using field-theoretic methods. Shape, energy, and effective diffusion constant of kink excitations are calculated, and their dependence on the bending rigidity of the semiflexible polymer is determined. For symmetric potentials, the kink motion is purely diffusive whereas kink motion becomes directed in the presence of a driving force. We determine the average velocity of the semiflexible polymer based on the kink dynamics. The Kramers escape over the potential barriers proceeds by nucleation and diffusive motion of kink-antikink pairs, the relaxation to the straight configuration by annihilation of kink-antikink pairs. We consider both uniform and point-like driving forces. For the case of point-like forces the polymer crosses the potential barrier only if the force exceeds a critical value. Our results apply to the activated motion of biopolymers such as DNA and actin filaments or of synthetic polyelectrolytes on structured substrates.     

Two-Component Solitary Waves in Hydrogen-Bonded Molecular Systems

The dynamics of two-component solitary waves in hydrogen-bonded chains in an external force and damping is investigated. The influence of the motion and the optical mode of the heavy ion sublattice on the portion sublattice is discussed. It will increase the soliton width and decrease the soliton mobility. The general expression for the kink soliton soliton is obtained. The velocity, the mobility and conductivity of the kink soliton are calculated. The results are in good agreement with the experimental data.     

Si中30度部分位错弯结运动特性的分子模拟

首先使用分子动力学方法(MD)得出了左弯结(LK)和右弯结(RK)在不同温度和剪应力作用下的速度特性和运动过程.然后利用基于紧束缚势(TB)的nudged elastic band(NEB)方法计算LK和RK的迁移势垒.由计算结果得出,单个LK或RK的势垒很高,运动速度相对较慢;LK中的多弯结对结构和由RK分解产生的右弯结-重构缺陷(RC)能够加速位错运动;其中,RC能促进30°部分位错更快地迁移.     

Dynamical behavior of the kink motion in carbon nanotubes

By performing molecular dynamics calculations, we studied the motion of the kink between two carbon nanotubes. Based on the sequential evaporation of the most energetic carbon atom, our calculations show that the kink has complex longitudinal and spiral motions, in good agreement with the experiments. The kink moves towards the nanotube of larger diameter, resulting in an overall diameter shrinking of the nanotubes without inducing any disorder or damage. The kink motions are found to be dependent on the chirality of the nanotubes. The kink connecting two zigzag nanotubes can have either a pseudoclimb or a spiral motion, while the kink between the armchair nanotubes has an interesting spiral motion with periodic split and recombination of the topological defects.