排序方式: 共有31条查询结果,搜索用时 15 毫秒
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应用改进分析型嵌入原子方法(MAEAM)计算fcc金属的结构稳定性和声子谱.考虑更远邻原子之间的相互作用,提出新的两体势函数,并采用新的截尾处理函数和加强光滑连接条件.通过拟合单空位迁移能、结合能、三个独立弹性常数及晶体平衡条件,确定了模型参数.在体积不变条件下,计算金属不同结构的能量,说明Ag、Al、Au、Cu、Ir、Ni、Pd、Pt和Rh的fcc结构比较稳定.它们的能量-体积曲线与Rose方程结果基本一致,进一步说明了体积变化时的结构稳定性.同时发现[100]、[110]和[111]三个方向声子谱的计算结果符合实验值和其它计算结果. 相似文献
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Jian-Min Zhang Xiang-Lei Song Ke-Wei Xu 《Journal of Physics and Chemistry of Solids》2006,67(4):714-719
The structures and energies of formation and migration of the mono- and di-vacancy in Cu crystal have been described and calculated with modified analytical embedded atom method (MAEAM). The lattice relaxation is considered with molecular dynamics (MD) method at T=0 K. The results show the FN di-vacancy is the most stable and likely occurs in practice from the energy minimization. Compared with the mono-vacancy, the formation energy of the FN di-vacancy is higher than that of a mono-vacancy, but lower than that of two isolated mono-vacancy. The preferred migration mechanism of the FN di-vacancy is multi-jump of either vacancy (rotating the di-vacancy). The calculated migration energy of the FN di-vacancy is lower than that of a mono-vacancy, so the FN di-vacancy is easier to migrate. All of the calculated results are in good agreement with the experimental values. 相似文献
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《Surface and interface analysis : SIA》2004,36(11):1500-1504
The unrelaxed energies for Ag(001) twist grain boundaries (GBs) have been calculated using the modified analytical embedded atom method (MAEAM). The results show that, besides zero energy in a perfect crystal (corresponding to the twist angle 0°), the second smallest GB energy corresponds to the twist angle 36.87°. This is consistent with the experimental results. For other twist angles, the GB energies remain nearly constant even for a twist angle as small as 1.94°. Translation parallel to the boundary plane could result in a periodic change in GB energy. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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The favorable position of an adatom and the formation energies of a single vacancy and an adatom‐vacancy pair in three low‐index surfaces of body‐centered cubic (BCC) transition metals have been calculated by using the modified analytical embedded atom method (MAEAM). The favorable position of an adatom is at the fourfold and twofold positions above the (100) and (110) surfaces respectively, but it is deviated from the threefold position of the (111) surface. Either the heights of the adatom from the top atomic layer, or the formation energies of a single vacancy, or an adatom‐vacancy pair decrease in sequence of the (110), (100) and (111) surfaces for each metal. Furthermore, the formation energy of an adatom‐vacancy pair is always lower than that of a single vacancy for each low‐index surface of each metal, which shown the formation of adatom‐vacancy pair is more energetically favorable than the vacancy for the BCC transition metals. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Yan‐Ni Wen Yan Zhang Jian‐Min Zhang Ke‐Wei Xu 《Surface and interface analysis : SIA》2011,43(12):1486-1490
The structural properties, the formation and migration energies of a single vacancy migrating intralayer and interlayer in the CuAu‐terminated (110) surface of Cu3Au ordered alloy have been calculated and discussed by using the modified analytical embedded‐atom method (MAEAM) and molecular dynamics (MD) methods. The surface layer exhibits rippling that the Au atoms are raised above Cu atoms about 0.117 Å in the topmost layer. The displacements of the topmost two layers are comparatively larger, while the third layer relaxes slightly and there are no changes in the nether layers. From energy minimization, the vacancy is most likely to be formed in the first layer (1L), especially on the Au site. The surface vacancy shows the smallest formation energy compared to the interlayer and bulk vacancies, while the corresponding value converges after the fifth layer (5L). For Cu vacancy originally sited in the second layer (2L) and migrated intralayer and interlayer, the diffusion without causing the local disorder is the most favorable, and the vacancy tends to migrate to the topmost layer. In the topmost layer of the CuAu‐terminated (110) surface, the circularity path is preferred over the beeline path. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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The structural stability and theoretical strength of FCC crystal Ag under uniaxial loading have been investigated by combining MAEAM with Wang modified Born stability criteria. The results reveal that, under sufficient compression, there exists a stress-free BCC phase, which is unstable and slips spontaneously to a stress-free mBCT phase by consuming internal energy. The stable region ranges from −2.076 to 4.390 GPa in the theoretical strength or from −7.972% to 8.721% in the strain correspondingly. The calculated structural energy difference between the BCC and FCC phase is in good agreement with the experimental value. 相似文献
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本文将元素变量(φ*和nWS)和MAEAM相结合,从原子尺度上对10种fcc金属Cu,Ag,Au,Ni,Pd,Pt,Rh,Al,Ir和Pb的38个不同晶面的表面能进行模拟计算及各向异性分析. 结果表明,fcc金属的密排面(111)的表面能最小,则该晶粒取向优先生长,与实验结果和第一原理的LMTO-ASA计算结果一致;各个晶面的表面能均随着其他晶面与(111)晶面的夹角cosθ(hkl)的增长而呈线性
关键词:
FCC金属
MAEAM
表面能
表面偏析 相似文献
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The surface relaxation and surface energy of both the mixed AuCu and pure Cu terminated Cu3Au (0 0 1) surfaces are simulated and calculated by using the modified analytical embedded-atom method. We find that the mixed AuCu termination is energetically preferred over the pure Cu termination thereby the mono-vacancy diffusion is also investigated in the topmost few layers of the mixed AuCu terminated Cu3Au (0 0 1) surface. In the mixed AuCu terminated surface the relaxed Au atoms are raised above Cu atoms for 0.13 Å in the topmost layer. All the surface atoms displace outwards, this effect occurs in the first three layers and changes the first two inter-layer spacing. For mono-vacancy migration in the first layer, the migration energies of Au and Cu mono-vacancy via two-type in-plane displace: the nearest neighbor jump (NNJ) and the second nearest neighbor jump (2NNJ), are calculated and the results show that the NNJ requires a much lower energy than 2NNJ. For the evolution of the energy requirements for successive nearest neighbor jumps (SNNJ) along three different paths: circularity, zigzag and beeline, we find that the circularity path is preferred over the other two paths due to its minimum energy barriers and final energies. In the second layer, the NN jumps in intra- and inter-layer of the Cu mono-vacancy are investigated. The calculated energy barriers and final energies show that the vacancy prefer jump up to a proximate Cu site. This replacement between the Cu vacancy in the second layer and Cu atom in the first layer is remunerative for the Au atoms enrichment in the topmost layer. 相似文献
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采用改进分析型嵌入原子法计算了Ag(111)//Ni(001)和Ag(001)//Ni(111)扭转界面的能量,结果表明:对Ag(111)//Ni(001)界面,当扭转角等于0°(或30°)时界面能最小,这一择优扭转角取向和Gao等人的实验结果一致;同样,对Ag(001)//Ni(111)界面,当扭转角等于0°(或30°)时界面能最小;从界面能最小化考虑,Ag(001)//Ni(111)扭转界面的择优扭转角也为0°(或30°).
关键词:
Ag/Ni界面
界面能
计算
改进分析型嵌入原子法
近重合位置点阵 相似文献