玻色-爱因斯坦凝聚体在光势阱中的量子隧穿

微观粒子因具有波动性而能以一定的概率穿过比它动能更高的势垒，这一现象称为隧道效应，玻色-爱因斯坦凝聚体在不同的囚禁势阱中表现出不同的隧穿特性，文章作者用周期瞬子方法首次研究了光势阱中玻色-爱因斯坦凝聚体的量子隧穿，研究表明，处在光势阱中的玻色-爱因斯坦凝聚体不仅表现出Landau-Zenner隧穿，而且出现新的Wannier-Stark隧穿，Wannier-Stark隧穿系数大约是Landu-Zener隧穿系数的1000倍，并得到了隧穿率随温度的变化规律，包括经典热激活、热助隧穿和量子隧穿，理论的计算结果与Yale大学和意大利INFM研究组关于Landau-Zener隧穿的实验结果相符合，同时给出了如何在实验上发现Wannier-Stark隧穿的参数区间。     

外加磁场下铁的形核机理

本文采用直接冷却和两相模拟两种分子动力学方法,研究了外加磁场液态铁凝固过程的影响并将结果与无外加磁场的计算结果进行对比. 外加磁场对凝固过程的影响主要体现在临界温度、能量和径向分布函数. 计算结果表明,铁液的凝固相变过程主要是发生在1500∽1600 K的温度范围;在外加磁场作用下,液态铁的凝固点有明显减小的趋势. 通过对扩散系数和粘度的进一步分析,在外加磁场的存在下,体系的扩散系数增大而粘度减小,研究显示外磁场驱动的铁液原子涨落较强导致凝固点的降低.     

基于珠串分子动力学的漫游反应H+MgH的反应速率研究

本文使用珠串分子动力学计算了多通道漫游反应H+MgH→Mg+H₂的热速率系数,明确考虑了两个反应通道：紧致和漫游通道. 首次将珠串分子动力学方法应用于多通道反应. 借助新开发的方法,即用于准备初始结构的优化插值工具和自适应的力常数选择方法,成功获得了热速率系数. 本文结果与其他理论方法,如变分过渡态理论和量子动力学结果一致. 珠串分子动力学速率结果显示出速率对温度的负相关性,这与变分过渡态理论的结果相似,但与基态量子动力学的结果不同.     

Dynamic Localization of a One—Dimensional Quantum Dot Array in an ac Electric Field

We investigate the dynamics of two interaction electrons confined to one-dimensional quantum dot array in an ac electric field.We find that initially localized electrons will remain localized in the absence of coulomb interaction if the ratio of the ac field magnitude to the frequency is a root of the ordinary zero-order Bessel function.In contrast to the case without Coulomb interaction,no matter what the value is,the electrons are delocalized and the delocalization effect depends on the ratio U/ω and eaE/ω,where U is the strength of Coulomb interaction,a is the lattice constant,and E and ω are the ac field amplitude and frequency,respectively.     

Simulation of Z-Pinch Processes of Nested Tungsten Wire-Array on Angara-5-1 Facility

Based on the hydrodynamic shell-on-shell collision model, the Z-pinch processes of nested tungsten wire-array in Sino-Russian joint experiments on Angara-5-1 facility are simulated by means of our one-dimensional three-temperature radiation magneto-hydrodynamic code. The results show the evolutions of x-ray radiation burst, implosion trajectories of interfaces, current transfer in inner and outer wire-array plasmas, and the temporal and spatial changes of magnetic field and current density in the process. About 20% of the total driven current is transferred into the inner wire-array plasma by convection and diffusion of magnetic field when the two shells are pinched closest. Compared to the measured x-ray power, the simulated full width at half maximum and time at the strongest radiation agree approximately with the measured values. It is also demonstrated in our simulation that the radiation of nested wire-array Z-pinch is enhanced. The effects of fluctuations of driven current on yields of x-ray are also investigated.     

于串珠分子动力学的Cl+XCl→XCl+Cl(X=H，D，Mu)反应的速率系数和动力学同位素效应研究

本文用串珠分子动力学计算典型的重-轻-重反应Cl+XCl→XCl+Cl(X=H,D,Mu)的热速率系数和动力学同位素效应. 对于Cl+HCl反应,串珠分子动力学方法计算得到的结果与实验值之间的高度一致性为串珠分子动力学理论的准确性提供了有力的证据. 串珠分子动力学结果也与其他理论方法的计算结果相一致,包括正则变分过渡态理论和量子动力学方法. Cl+MuCl反应在过渡态附近存在势能双峰,留下了自由能阱,它来自于势能面峰值处反应系统的模式软化. 同时,如此明显的自由能阱表明存在反应共振. 对于Cl+DCl反应,与实验值相比,串珠分子动力学速率系数再次给出了非常准确的结果. 唯一的例外是在312.5 K的温度下,串珠分子动力学速率系数和其他理论方法计算得到的结果彼此接近,却略低于实验值,表明误差可能源于实验测量或本文使用的势能面不够精确.