一种Monte Carlo仿真新算法及其对三维个体晶粒长大速率拓扑依赖？…

通过建立一种新的三维晶粒组织及其演变的Ｍｏｎｔｅ Ｃａｒｌｏ可视化图像仿真算法，验证了作者近年来理论导出的三维个体晶粒长大速率拓扑依赖性方程的正确性。     

三维晶粒长大速率方程的大尺度Ports模型Monte Carlo仿真验证

采用Potts模型Monte Carlo方法对3种现存的三维个体晶粒长大速率拓扑依赖性方程进行了仿真验证．结果表明,Rivier速率方程认为晶粒体积变化率dVf／dt与晶粒面数f成线性关系,与仿真结果明显不符,不适用于描述三维晶粒长大过程的动力学．当晶粒面数f≥8时,Yu—Liu速率方程和MacPherson-Srolovitz速率方程均与仿真结果很好吻合,表明这两者均可以用来定量描述三维晶粒长大过程的动力学;当f〈8时,这两个方程均与仿真结果有显著差异．     

三维晶粒长大速率方程的大尺度Potts模型Monte Carlo仿真验证

采用Potts模型Monte Carlo方法对3种现存的三维个体晶粒长大速率拓扑依赖性方程进行了仿真验证.结果表明,Rivier速率方程认为晶粒体积变化率dVf/dt与晶粒面数,成线性关系,与仿真结果明显不符,不适用于描述三维晶粒长大过程的动力学.当晶粒面数f≥8时,Yu-Liu速率方程和MacPherson-Srolovitz速率方程均与仿真结果很好吻合,表明这两者均可以用来定量描述三维晶粒长大过程的动力学;当f<8时,这两个方程均与仿真结果有显著差异.     

ON THE MONTE CARLO SIMULATION OF NORMAL GRAIN GROWTH

The microstructures and their kinetics of normal grain growth are simulated using different Monte Carlo （MC） algorithms. Compared with the relative figures and the theoretical normal grain growth exponents of n =0.5, the effects of some factors of MC algorithm, i.e. the lattice types, the methods of selecting lattice sites, and the neighbors selection for energy calculations, on the simulation results of grain growth are studied. Two methods of regression were compared, and the three-parameter nonlinear regression is much more suitable for fitting the grain growth kinetics. A better model with appropriate factors included triangular lattice, the attempted site randomly selected, and the first and second nearest neighbors for energy calculations is obtained.     

A MONTE CARLO SIMULATION OF THE CVD DIAMOND FILM

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Pt-Rh二元合金系表面偏聚的分析型EAM模型计算

应用分析型EAM多体势和Monte Carlo模拟方法研究了Pt-Rh合金系的表面偏聚情况．模拟结果显示，不同Pt含量的合金以及不同的表面，最外层都富集Pt原子，次外层富集Rh原子，剖面成分呈振荡分布．(111)面和(100)面的成分偏聚量差别较大：(111)面的Pt原子偏聚量较(100)面小得多，且前者只有最表面3层原子发生偏聚，而后者的成分偏聚影响表面至少10层．模拟结果与已有理论和实验结果符合得很好．     

LiF-KF熔盐溶液热力学性质Monte Carlo法计算机模拟研究

本文用 Monte Carlo法对同离子系LiF-KF熔盐溶液的结构和性质进行了计算机模拟.对各离子间的偏径向分布函数和混合热、位能分布等的计算表明,LiF与KF熔盐混合后,Li~+,F~-离子间平均距离减少,与互易盐系LiF-KCl溶液的模拟结果相似.混合热的计算结果与实测值相当接近。混合热产生的原因:正离子间排斥能减少;正负离子间吸引能减少;负离子间排斥能减少。     

纯铜动态再结晶的Monte Carlo法模拟

本文建立了一种基于能量判据的确定动态再结晶各个阶段临界应变的方法，并基于此种方法Monte Carlo(MC)法进行了纯铜动态再结晶的二维模拟，定量计算了变形引起的存储能与变形之间的关系，计算出了发生动态再结晶的临界应变。模拟结果表明，采用MC法可以揭示动态再结晶的形核生长过程与应变历史之间的关系。结合本文所建立的基于能量判据的确定动态再结晶各个阶段临界应变的方法，可以预测开始发生动态再结晶的临界变形条件。     

MONTE CARLO SIMULATION OF SPIN-POLARIZED SECONDARY ELECTRONS FROM IRON

A Monte Carlo model considering the electron spin direction and spin asymmetry has been developed. The energy distribution of the secondary electron polarization and the primary energy dependence of the polarization from Fe are studied. The simulation results show that: (1) the intensity of the spin-up secondary electrons is larger thanvthat of thevspin-down secondary electrons, suggesting the secondary electrons are spin polarized; (2) the spin polarization of secondary electrons with nearly zero kinetic energy is higher than the average valance spin polarization, Pb=27% for Fe. With increasing kinetic energy, the spin polarization of the secondary electrons decreases to the value of Pu remaining constant at higher kinetic energies; (3) the spin polarization increases with an increase in the primary energy and reaches a saturation value at higher primary energy in both the Monte Carlo simulation and experimental results.     

COMPUTERIZED SIMULATION OF THERMODYNAMICS FOR MOLTEN LiF-KF SOLUTION BY MONTE CARLO METHOD

The structure and behaviour of LiF-KF solution,as a typical common-anion system,hasbeen simulated by Monte Carlo method.The calculation of partial radial distribution functionof ions,heat of mixing and potential energy distribution shows that the average distance be-tween Li~+ and F~- ions will significantly narrow after mixing of molten LiF and KF.This isvery similar to the lean-on-one-side effect in molten LiF-KCl solution.The calculated heatof mixing is in fair agreement with the measured one.The dominant source of the energy ofmixing may be that the decrease of the repulsion energy between cations,the decrease of theattraction energy between cations and anions,and the decrease of the repulsion energy be-tween anions.     

MONTE CARLO SIMULATION STUDY OF SURFACE ELECTRONIC EXCITATION OF NOBLE METALS

1. IntroductiollThe study of inelastic scattering of electrons in a surface region is important to thecomprehensive understanding of the basic process of electron-surface interaction in a surfaceelectron spectroscoPy Recently study of the surface energy l…