中速C3+与Ne原子靶相互作用过程中单电子转移绝对截面的测量

实验测量了2.2v₀—4.2v₀(v₀为玻尔速度,v₀=2.19×10⁸cm/s)的C³⁺与Ne原子碰撞过程中单电子转移绝对截面.将实验结果与多体经典轨道蒙特卡罗模拟计算结果进行了比较.用电离能的变化、屏蔽效应、动态关联对实验和理论计算结果间的数值差异做了分析.总体上,实验结果与多体经典轨道蒙特卡罗方法计算结果在趋势上相 关键词： 离子-原子碰撞 单电子转移 绝对截面     

Guiding of 150 keV O6＋ ions through nanocapillaries in an uncoated Al2O3 membrane： special time dependence of the transmission profile width

<正>This paper reports that the transmission of O⁶⁺ ions with energy of 150keV through capillaries in an uncoated Al₂O₃ membrane was measured,and agreements with previously reported results in general angular distribution of the transmitted ions and the transmission fractions as a function of the tilt angle well fitted to Gaussian-like functions were observed.Due to using an uncoated capillary membrane,ourψ_c is larger than that using a gold-coated one with a smaller value of（?）,which suggests a larger equilibrium charge Q_∞in our experiment.The observed special width variation with time and a larger width than that using a smaller（?） were qualitatively explained by using mean-field classical transport theory based on a classical-trajectory Monte Carlo simulation.     

Single electron loss in and atomic the collisions of C^3＋ hydrogen

This paper studies the projectile electron loss cross sections of C^3＋ colliding with atomic hydrogen in the frame work of extended over-barrier model at intermediate velocities （25 keV/u-600 keV/u）. The electron loss is calculated in terms of the interaction between the screened target nucleus and the active projectile electron and of the interaction between projectile electron and target electron. Compared with the convergent close-coupling calculations, screening and anti-screening calculations, this model satisfactorily reproduces the experimentally obtained energy dependence of the electron-impact ionisation cross sections and the single electron loss cross sections over the energy range investigated here.     

Quantum Thermal Transport through Extremely Cold Dielectric Chains

In the framework of Green＇s function theory out of equilibrium, a Landauer-Buttiker （LB） formula for thermal conductance is derived. A simplified model for describing extremely cold dielectric chains is proposed for the first time. Further we apply the present LB formula for studying thermal conductance at low-lying modes, emerging in dielectric atom chains. We find that quantum thermal conductance undergoes an anomalous transition due to new quasiparticle excitations, resulting from nonlinear atom-atom interactions. This theoretical prediction is in excellent agreement with a high-accuracy measurement to thermal conductance quantum.     

New Monte Carlo Simulations to a Generalized XY Model

A new combination Monte Carlo （MC） technique of the classical Metropolis algorithm and the Swendsen Wang cluster algorithm is proposed. Upon application of the MC technique, the thermodynamic properties of a generalized two-dimensional XY model with chiral Dzyaloshinski-Moriya （DM） interactions are simulated for various DM interactions. The specific heat, order parameter and the integrated correlation time are simulated, We find that there exists a high-temperature Kosterlitz-Thouless-type phase transition related to strong DM spin ehiralities. As the DM strength increases the critical temperature of the Kosterlitz-Thouless phase transition increases, It is shown that the combination algorithm is faster than the Metropolis algorithms.     

基于GIS广州市主城区地面塌陷危险性评价

地面塌陷是珠江三角洲城市地质灾害的主要类型之一。广州市主城区地面塌陷频繁发生且损失严重。采用信息量数学模型与GIS技术结合对其地面塌陷灾害进行危险性评价。选取了断裂构造、地壳稳定性、第四系覆盖层厚度、基岩岩性、地下水动力条件、地表人类活动强度和地下活动强度等7个指标中的21个变量构建了危险性评价指标体系,应用ArcGIS软件参与了数据的采集、管理、分析和评价结果表达等过程,将广州市地面塌陷灾害危险性分为极不稳定级、不稳定级、次不稳定级、基本稳定级和稳定级5个等级,极不稳定级主要分布在主城区西北角,次不稳定级分布面积最广。研究结果表明:复杂的地质环境和剧烈的人类活动相耦合,加剧了地面塌陷的发生。     

基于粒子成像测速技术的水中气泡界面的光学性质研究

基于粒子成像测速的流体可视化技术，根据菲涅耳公式计算了入射到水中气泡界面的光强，得出点光源连续两次反射或折射的光强具有等比数列的规律，光线在气泡界面反射、折射4次就变成完全偏振光且光线几乎消失.当入射角避开35°左右时，即便有一定宽度的线光源入射到气泡界面，第2次折射出气泡的光强与线光源的宽度无关，类似一条光线入射所产生的光强，给出了面光源在界面所产生的光强的二重积分表达式.线光源所产生的界面光强理论值、面光源产生的光强数值解与实验值都较为符合. 关键词： 水中气泡 界面 光强 粒子成像测速     

Electronic and Magnetic Properties of Double Perovskite Ca2CrSbO6

First-principles calculations have been performed for the study of the electronic band structure and ferromagnetic properties of double perovskite Ca2CrSbO6. The density of states, total energy, spin magnetic moment, and charge density were calculated and analyzed in details. It is found that Ca2CrSbO6 has a stable ferromagnetic ground state and the spin magnetic moment per molecule is about 2.99#B. The chromium contributes the most in the total magnetic moments. The results indicate that Ca2CrSbO6 is half-metallic.     

高温稠密气态混合物质压强的计算

 基于含温有界相对论自洽场平均原子模型,计算了高温稠密条件下气态混合物的压强。通过求解相对论Dirac方程给出有界原子的电子波函数和轨道能量。电子在各单电子轨道上的平均占据数服从Fermi-Dirac分布。以铝、铝镁混合物、铁和高能炸药HMX（奥克托金）为算例,计算了在一些温度密度点下的压强并给出了分析。     

中低速C3+与He,Ne,Ar原子相互作用过程中单电子转移绝对截面的测量

实验测量了1.7v0-4.2v0(v0为玻尔速度,v0=2.19×108 cm/s)的C3+与He,Ne,Ar原子碰撞过程中单电子转移绝对截面.将实验结果与多体经典轨道蒙特卡罗模拟计算结果做了比较,发现测量结果与多体经典轨道蒙特卡罗模拟计算结果在趋势上相符.当入射离子速度在1.7v0-2.0v0时,因多体经典轨道蒙特卡罗方法计算时不能考虑多电子关联态俘获和极化效应的影响,实验值大于计算值.当入射离子速度在2.2v0-4.2v0时,由于被俘获电子对入射离子的不完全屏蔽,加上电子间的动态关联及有效电荷的影响,实验结果先与多体经典轨道蒙特卡罗计算结果符合很好,而后逐渐大于计算值.此外,还根据转移电离与单电子俘获的截面比简单分析了转移电离机制.