Surface Effects on Wannier Excitons in Superlattices:Monte Carlo Simulation

Using a Monte Carlo quadrature,we calculate by a variational method the binding energy Eb of Wannier excitons in N-period m-CdMnTe/n-CdTe superlattices,including or not including the step discontinuity in the potential barrier at the interface,and with varying N as well as well width.The calculation is performed in the framework of the effective mass approximation for both heavy-hole and light-hole excitons.The degree of exciton localization dependence on these parameters is accurately illustrated.     

Effect of Precursor Mechanism on CO-NO Catalytic Reaction on Body-Centred Cubic Structure： Monte Carlo Simulation

The CO-NO catalytic reaction on body-centred cubic （bcc） lattice is studied by Monte Carlo simulation. The simple Langmuir-Hinshelwood （LH） mechanism yields a steady reactive window, which is separated by continuous and discontinuous irreversible phase transitions. The effect of precursor mechanism on the phase diagram of the system is also studied. According to this mechanism, the precursor motion of CO molecules is considered only on the surface of bcc lattice. Some interesting observations are reported.     

Monte Carlo Simulation of Kinesin Movement with a Lattice Model

Kinesin is a processive double-headed molecular motor that moves along a microtubule by taking about 8nm steps. It generally hydrolyzes one ATP molecule for taking each forward step. The processive movement of the kinesin molecular motors is numerically simulated with a lattice model. The motors are considered as Brownian particles and the ATPase processes of both heads are taken into account. The Monte Carlo simulation results agree well with recent experimental observations, especially on the relation of velocity versus ATP and ADP concentrations.     

二元合金表面偏析的Monte Carlo方法模拟

详细介绍了二元合金表面偏析的Monte Carlo模拟方法,并应用改进的分析型嵌入原子模型结合Monte Carlo方法模拟研究了Pd-Au合金表面成分及其剖面成分分布,发现Au在表面偏析,并同已有实验结果进行了比较.     

Monte Carlo Simulations of Mixed Highly Frustrated Systems

We have performed Monte Carlo simulations on the mixed highly frustrated K2CuxMn1-xF4 and FexMn1-xTiO3 systems.Transitions of random systems with well-established universality classes are obtained.This study allows us to investigate mainly the usual and re-entrant spin glass and criticality associated with these states.The ratio x of substitution (or dilution)is found to have a large influence on the nature of this criticality.     

具有表面弛豫的液体自扩散的Monte Carlo模拟

研究多孔介质中液体的自扩散行为能获得介质的微观结构信息,有助于了解介质中液体的传输性质.以具有不同孔隙大小的无限长圆柱体模型中的液体为对象,采用Monte Carlo随机行走方法,模拟存在表面弛豫时液体的自扩散系数和核自旋磁化强度随时间的变化,导出将NMR弛豫参数和随机行走参数联系在一起的表达式.结果表明:在快扩散区,液体的核自旋磁化强度随弛豫时间呈单指数衰减,且自扩散系数在短时情况下独立于表面弛豫率;在慢扩散区,液体的核自旋磁化强度衰减和自扩散系数在短时情况下均与表面弛豫率无关.模拟结果与理论分析相吻合,可用于求解介质的表面积与体积之比及孔径大小等结构信息.     

Monte Carlo Simulation of Opacities of Hot and Dense Au Plasma in the Unresolved Transition Array Approximation

The opacity,and its Planck and Rosseland mean values,of the hot and dense Au plasma in local thermodynamics equilibrium are studied by the Monte Carlo method based on the unresolved transition array (UTA) approximation.The average ion model and the Saha equation are used to determine the atomic level populations.The result gives a more detailed structure for frequency-dependent opacity than the popularly used super transition array or UTA in the photon energy range of 500eV to 2000eV.The Monte Carlo method can give a result better than that of the UTA,with almost the same computation effort.     

材料中He深度分布演化的Monte Carlo模拟研究

基于He泡生长的迁移-合并机理,用Monte Carlo方法模拟了对材料进行等温退火过程中He深度分布的演化,探讨了不同参数对这一演化的影响.研究表明:材料中He泡的初始浓度和尺寸将影响He深度分布的变化,而退火温度则对演化速率起重要作用但对最终的He深度分布影响较小;随着反应的进行,整个系统的演化是逐渐趋缓的. 关键词： He 深度分布 Monte Carlo模拟     

A standard Event Class for Monte Carlo Generators

StdHepC [1]is a CLHEP[2] Monte Carlo event class library which provides a common interface to Monte Carlo Event Generators,This work is an extensive redesign of the StdHep Fortran interface to use the full power of object oriented design,A generated event maps naturally onto the Directed Acyclic Graph concept and we have used the HepMC classes to implement this.The full implementation allows the user to combine events to simulate beam pileup and access them transparently as though they were a single event.     

不同温度下团簇生长的Monte Carlo模拟

引入基底表面束缚能、最近邻粒子间的耦合能以及应力场,对粒子扩散势垒进行修正,采用Monte Carlo方法对不同温度下薄膜生长过程进行模拟研究.结果表明,当400 K≤T ≤ 480 K,所得团簇的平均分支宽度基本保持不变,其值近似为单粒子直径.当500 K≤T ≤ 680 K,团簇分支宽度随着温度的升高而逐渐增大至约4个粒子.随着温度的继续升高,由于粒子较高的活跃性而无法凝聚形成大团簇,团簇包含粒子数的平均值小于2.还研究了不同温度下团簇在生长过程中的形貌演化过程以及团簇数变化规律.     

投影电子束光刻中电子穿透掩膜的Monte Carlo模拟

利用基于Mott散射截面和介电函数模型的Monte Carlo方法模拟了电子穿透掩膜的能量损失分布，其计算结果与实验结果符合很好. 由此进一步计算了角度限制投影电子束光刻(SCALPEL)掩膜的穿透率和衬度，结果表明：散射体的厚度对衬度的影响较大，衬度随散射体厚度的增加而增强，而支撑体对衬度的影响较小；增大限制孔的孔径角时，透射率相应增大，但衬度会降低；衬度随入射电子的能量增加而减小. 关键词： Monte Carlo模拟 电子束光刻 掩膜     

Effect of Ballistic-Type Hot Atom Adsorption Mechanism on the Phase Diagram of Monomer Dimer CO-O2 Surface Catalytic Reaction： A Monte Carlo Simulation

We investigate the effect of the ballistic mechanism on the phase diagram using a square surface. While using this mechanism whenever an O2 molecule hits a randomly vacant selected site, the molecule breaks up into atomic form and othen executes a ballistic flight. The paths of the two oxygen atoms are taken exactly to be opposite to each other, i.e. anti-parallel, and the ranges of the atoms are taken to be equal, i.e. they may fly up to 1 or 1.414 or 2 of the atomic spacing from the site of impact. Four cases have been studied on the basis of the range of hot atoms. The range of the hot oxygen atoms executing a ballistic flight might be up to the first nearest neighbourhood (1 atomic spacing from the site of impact),the second nearest neighbourhood(1.414 atomic spacing from the site of impact), the third nearest neighbourhood (2 atomic spacing from the site of impact), known as cases a, b, and c, respectively,while for case d the rane of the oxygen atoms executing the ballistic flight might be up to 1atomic spacing or 1.414 atomic spacing or 2 atomic spacing from the site of impact. The steady reactive window is observed and the continuous transition disappears. As soon as the CO partial pressure departs from zero, the production of CO2 is observed, which clearly verifies the experimental observation.     

6H-SiC电子输运的Monte Carlo模拟

从实际测量和单粒子Monte Carlo模拟两个方面研究了6H-SiC的电子输运规律,在模拟中考 虑了6H-SiC主要的散射机理,模拟的结果体现了6H-SiC具有良好的高温和高场特性以及迁移 率的各向异性,其横向迁移率和纵向迁移率相差近5倍.模拟结果和实验数据的对比说明了对 6H-SiC输运特性的模拟是正确的. 关键词： 6H-SiC Monte Carlo模拟 迁移率 散射机理     

τ质量测量方案的Monte Carlo研究

在τ质量实验测量之前对多种测量方案进行了细致的Monte Carlo研究,并进行了比较.确定τ质量测量实验采用最大似然法,并给出可能的测量精度.研究了包括探测效率、束流能散等诸多因素对实验的影响,同时对实验的实现提出要求.     

Monte Carlo方法模拟低能电子在Al中的散射

基于文献[1]的工作,电子在固体中的弹性散射用Mott微分截面计算;非弹性散射分为单电子激发和等离子激发并由Streitwolf、Gryzinski及Quinn的截面描述.模拟了低能电子在Al块样及薄膜中的散射过程,对不同能量低能电子作用下Al的背散射系统、能谱又透射系数作了计算,结果与实验符合较好.也对背散射电子、低能损背散射电子表面分布作了计算,结果表明低能损背散射电子具有较好的空间分辨率.     

H+2团簇与固体相互作用的Monte Carlo模拟

讨论了H+2团簇在物质中的作用过程, 包括库仑爆炸过程、尾流势的影响和与靶原子的近碰撞等. 开发成功了一套适用于不同靶材料的Monte Carlo模拟程序, 模拟计算了H+2通过碳膜后出射粒子的能谱和角分布, 并与实验结果进行了比较.     

高能电子束对抗蚀剂曝光的Monte Carlo模拟

利用分段散射模型, 借助Monte Carlo方法模拟了具有高斯分布特征的 高能入射电子束(50keV≤E₀≤100keV)在抗蚀剂中的 散射过程, 分别得到了不同曝光条件下的电子背散射系数和能量沉积分布, 模拟结果与实验结果很好地符合. 在这一能量段, 当电子束能量越高、抗蚀剂 越薄、基片材料的原子序数越低时, 邻近效应越弱. 本文的模拟结果不仅能为高能电子束光刻工艺优化曝光条件、降低邻近效应提供理论指导, 而且能为进一步的邻近效应的校正提供更精确的数据.     

Non-Thermal Effects on CO-NO Surface Catalytic Reaction on Square Surface： Monte Carlo Study

A Monte Carlo simulation of the CO-NO heterogeneous catalytic reaction over a square surface has already been studied with a model based on the Langmuir-Hinshelwood (LH) mechanism. The results of this study are well known. Here we study the effects of transient non-thermal mobility of monomer (CO) based on precursor mechanism, diffusion of adsorbed nitrogen and oxygen atoms, on the phase diagram. The interesting feature of this model is the yield of a steady reactiw window, while simple LH mechanism is not capable of producing a steady reactive state.     

静态随机存储器单粒子翻转的Monte Carlo模拟

利用蒙特卡罗(Monte Carlo)方法，对10—20MeV 中子在静态随机存储器(SRAM)中引起的单粒子翻转进行了模拟，着重对中子在SRAM 灵敏区引起的电离能量沉积进行了计算，并对中子引起单粒子翻转过程相关物理量进行了计算.这些计算模拟结果为了解10—20MeV 中子引起SRAM 单粒子翻转过程提供了详细的统计信息，为SRAM 的抗辐射加固提供相关参考信息. 关键词： SRAM单粒子翻转 Monte Carlo 模拟 能量沉积     

梯度场中荧光关联谱测量的Monte Carlo模拟

荧光关联谱（FCS）利用少量分子的荧光涨落获得分子运动和反应信息,是一种探测活细胞内生物过程的有力工具。本文利用Monte Carlo方法模拟激光梯度场下瑞利粒子的布郎运动,分析梯度场对FCS测量得到的扩散时间、粒子数等参数的影响,模拟与初步实验结果定性吻合。文中还讨论了Monte Carlo模拟预测的一些实验现象。