排序方式: 共有68条查询结果,搜索用时 375 毫秒
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任何热力学量的涨落在平衡态下都不能太大.特别地,要求熵和能量的涨落不大,就可以给出低温下热力学平衡态的普遍适用的判据.一些算例表明,低温下即使1023个粒子也不一定能达到热力学平衡态. 相似文献
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采用分子动力学方法对六种不同冷却速率对液态金属Pb凝固过程中微观团簇结构演变的影响进行了模拟跟踪研究.采用双体分布函数、Honeycutt-Andersen键型指数法、原子团类型指数法(CTIM-2)、平均配位数等方法对凝固过程中微观团簇结构的演变进行了分析.结果表明:系统存在一个形成非晶态或晶态结构的临界冷速(介于5×1012与1×1012之间),大于这个临界冷速时,系统将形成以1551,1541和1431键型为主的非晶态结构;当小于这个临界冷速时,系统将先形成以1441和1661键型或以bcc基本原子团(14 6 0 8 0 0)为主的晶态结构,并稳定存在一段时间,然后又迅速转变为以1421和1422键型为主或以fcc基本原子团(12 0 0 0 12 0)和hcp基本原子团(12 0 0 0 6 6)以一定比例并存的部分晶态结构;同时发现,冷速对系统中fcc结构和hcp结构的相对比例有明显的影响,冷速越低,fcc结构所占的比例越多,越倾向于形成完美的fcc晶态结构.
关键词:
液态金属铅
凝固过程
团簇结构演变
分子动力学模拟 相似文献
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Pauli在处理无限深势阱中的单粒子时,要求粒子具有经典力学的能量动量关系E=p2/2m,而且混用了定波和定态的概念,这说明Pauli更多地用到的是半经典量子论而不是量子力学,他所得到的动量分布函数是半经典理论的结果,只有在大量子数极限下才与量子力学的结果趋于一致. 相似文献
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AN ALTERNATIVE ONE-PARTICLE QUANTUM THEORY WITH A NEW EXPECTATION VALUE POSTULATE 总被引:1,自引:0,他引:1 下载免费PDF全文
Our recent treatment of some single-particle systems implies that if the expectation value postulate in usual quantum theory is changed in some proposed way, we can also have a self-consistent and reasonable one-particle quantum theory. In this paper, the framework of the theory barmonized with a newly proposed self-energy quantum electrodynamics is given. Our theory is compatible with Einstein's completeness. It in statistical ensemble reproduces the results given by the usual theory and in classical limit reduces to the classical mechanics for the single-particle systems. 相似文献
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A technique of coordinate transformation is devised to overcome the computational difficulty associated with the direct transformation between eigenfunctions of three components of the geometric momentum on two-dimensional spherical surface, and the computations are firstly carried out in new coordinates and secondly the results are transformed back into the original coordinates. The eigenfunctions of different components of geometric momentum is explicitly demonstrated to transform under the spatial rotations in the precise way we anticipate. 相似文献