D03结构Fe3Al合金晶格动力学的嵌入原子模型计算

应用改进分析型嵌入原子模型，系统地计算了D03结构Fe3Al合金的晶格动力学性能，包括晶格常数、形成热、弹性常数、声子谱、态密度、摩尔定容热容、德拜温度和热膨胀系数等，并将计算结果与已有实验数据和其他理论计算结果进行了比较。计算所得声子谱相对于其他理论计算结果而言，与实验值的符合程度更好；计算的热膨胀量在低温区与实验结果基本一致，而在高温区明显偏低于实验结果。     

FORMATION ENTHALPIES FOR FCC METAL BASED BINARY ALLOYS BY EMBEDDED ATOM METHOD

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Development of embedded-atom potentials and prediction of properties for binary Ti-V

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Molecular dynamics simulation on thermodynamic properties of Pb-Ag alloys

Molecular dynamics simulation was used to simulate the thermodynamic properties of three binary alloys, Pb-Ag (1:1), Pb-Ag (4:1), and Pb-Ag (9:1). The energy functions, such as excess free energy, cohesive energy, and formation energy, were calculated. The calculated val-ues agree well with the experimental ones. The atomic interactions were analyzed in macroscopic and microcosmic views and both are con-sistent well.     

Multi-scale simulation study for growth dynamics of irreversible islands during submonolayer epitaxy

Using empirical embedded atom method (EAM) potential, activation barriers of adatom diffusion on the surface, diffusion along the step edge, and island corner diffusion are calculated for metal (111) surface (Pt, Ag) and the behavior of those barriers is investigated with respect to lattice strain. Based on the calculated barriers, we perform the kinetic Monte Carlo simulation for monolayer island growth and for how the variation of the activation barriers with lattice strain changes the island growth. Results from this work show that the lattice strain transforms the island growth shape from dendritic through random fractal to denditic at 100 K and from triangular through hexagonal to inverse triangular at 400 K. This article is based on a presentation made in the 2002 Korea-US symposium on the “Phase Transformations of Nano-Materials,” organized as a special program of the 2002 Annual Meeting of the Korean Institute of Metals and Materials, held at Yonsei University, Seoul, Korea on October 25–26, 2002.     

单晶镍纳米薄膜单向拉伸破坏的分子动力学模拟

应用分子动力学方法模拟了单晶镍纳米薄膜受单向拉伸破坏的过程, 得出纳米尺度单晶镍薄膜的应力-应变关系、能量演化曲线和镍薄膜构型的变化及微损伤的形成和扩展过程. 模拟采用原子镶嵌势描述原子间作用, 得到镍单晶薄膜的弹性模量, 分析了拉伸过程中系统原子能量、应力变化和外荷载的关系. 结果表明: 纳米薄膜的自由表面影响拉伸过程中原子的运动和薄膜整体力学性能, 纳米薄膜破坏的几何特征是原子空位的连接和晶胞缺陷的扩展; 单晶的断裂接近脆性断裂, 模拟得到纳米薄膜的断裂强度符合Griffith脆性断裂的能量平衡理论.     

MEAM Potential with Angular Dependence for TiAl

Daw and Baskes [1] presented the embeddedatom method as an improved empirical potentialto overcome the shortcomings of the pair-potentials, and it has been used in model fee metalswith considerable success [2]. However, it doesnot include the angular character of valenceelectron, whieh is now recognized to be driportant in bee transition metals and illtermetalliccompounds [3]. For instance, the attempt tomodel the LI, smictule of TiAl using an EAMpotelltial gives an incorrect equilibrium st…     

贵金属-AI二元合金形成焓的EAM计算

运用嵌入原子方法（ＥＡＭ）计算了贵金属Ｃｕ,Ａｇ,Ａｎ,Ｎｉ,Ｐｄ;Ｐｔ;Ｒｈ;Ｉｒ和ＡＩ构成的８个二元系统的形成焓,计算结果与已有的实验结果以及Ｍｉｅｄｅｍａ理论计算的结果符合得比较好     

贵金属嵌入原子参数及贵金属二元合金稀溶解热的计算

采用修正的嵌入原子模型（modified embedded atom method，（MEAM）），给出了Cu，Ag，Au，Ni，Pd，Pt，Rh，Ir等元素的所有嵌入原子参数，用所给参数计算了上述元素的单空位形成能、双空位结合能、结构能量差及由它们构成的二元合金的稀溶解热。计算的稀溶解热与实验结果及已有的理论计算结果进行了比较，现在的计算值与已有的实验结果和Miedema理论计算结果符合得比较好。     

The effect of lattice strain on step edge diffusion

The effects of lattice strain on the step edge diffusion of Ag(111) and Ag(100) surfaces are analyzed using molecular statics (MS) based on the semi-empirical embedded atom method (EAM) potential. The calculation of activation barriers of adatom diffusion on surfaces, diffusion over step edge, island corner diffusion, and diffusion along step under strained conditions shows that lattice strain greatly affects the energy barriers of various diffusion processes. For example, comparison shows that the Ehrlich-Schwoebel (ES) barrier decreases as lattice strain increases, which is opposite with strain dependency of surface diffusion barrier, and the diffusions along two different types of steps on Ag(111) surface have a lattice strain dependency different from each other. These different diffusion barrier behavior dependencies on lattice strain have interesting implications on the morphological evolution of strained thin film. This article is based on a presentation made in the 2002 Korea-US symposium on the “Phase Transformations of Nano-Materials,” organized as a special program of the 2002 Annual Meeting of the Korean Institute of Metals and Materials, held at Yonsei University, Seoul, Korea on October 25–26, 2002.     

Pb-Au合金热力学性质的分子动力学模拟

使用分子动力学方法模拟Pb40Au60、Pb80Au20和Pb90Au103种合金的热力学性质,计算合金的过剩自由能、结合能和形成能等能量方程。结果显示:合金的形成能和过剩自由能均为正值,因此Pb-Au合金为正偏差体系。从微观和宏观角度分析原子间的相互作用,并且使用形成能定量描述合金与理想熔体的偏离程度。     

Aln(n=2～24,55)团簇结构特性的第一原理计算

采用第一原理赝势平面波方法计算Aln(n=2~24,55)团簇的几何、能态与电子结构,通过结合能Eb、HOMO-LUMO能隙ΔEH-L与能量二阶差分Δ2E(n)表征和考察团簇原子数n对Aln团簇基态结构稳定性的影响。结果表明:Aln团簇结构稳定性随团簇原子数n增加而增大,并在n为7,11,13,19,23等近幻数和高对称性结构处出现极值,相对其临近Aln团簇,具有较高的结构稳定性。DOS与吸收光谱分析表明,随着团簇内部s-p电子杂化的逐渐增强,Aln团簇结构的稳定性也随之增加,但即使当团簇原子数n达到55时,其微弱的表面效应仍不能消除。