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81.
Phonon modes in spherical Si quantum dots (QDs) with up to 7.9 nm
in diameter are calculated by using the projection operators of the group
theory into valence force field model. The phonons of dot modes in each of
five irreducible representations (symmetries) are classified by using a dual space analysis method. It is found that the bulk-like modes with localization radius much smaller than the dot's radius have clearly pronounced bulk specific-k point parentage, Tλ(n, kBZ,
Kcut), from specific part of the Brillouin zone (BZ) (Γ-derived,
X-derived etc.) and from definite bulk band (one in six modes).
In Si dots of all sizes, each specific bulk-like dot mode has specific symmetry. The bulk TO(Γ)-like and the bulk LO(Γ)-like dot modes always have T2 and
A1 symmetries, respectively. Except the bulk-A(Γ)-like dot modes of which the frequencies
blue-shift as the dot size reducing, the bulk-like Γ-derived LO
and TO dot modes and bulk-like
X-derived TA and LA dot modes red-shift in frequency with decreasing dot size. There is almost not LO/TO mixing for bulk-like modes. As for the surface-like modes localized at the periphery of the dot, their eigenmodes have not a dominant bulk specific-k point parentage or a dominant BZ parentage around some special point.
They are a superposition of many bulk bands with k from
all over the bulk BZ. They have much significant mode mixing than the
bulk-like phonons. The classification of dot modes based on the symmetry of group theory will bring advantageous to the discussion of Ramam spectrum, electron-phonon interaction and other phonon-assisted effects in QDs. 相似文献
82.
83.
以金川矿区为例,介绍了应用GIS进行二次开发来构建矿山地表移动信息管理与分析系统的方法、过程以及该系统的主要功能。该系统包括地表移动信息管理、地表移动分析与评价、地表移动预测3个模块,充分利用了GIS强大的空间数据管理与分析能力,实现了GIS与Surfer结合进行矿山地表移动分析与评价,GIS与Matlab结合进行监测数据的非线性神经网络时序预测。该系统不但有助于提高金川矿山地表移动信息的检索和分析效率,对其他矿山地表移动信息系统的建立也具有借鉴意义。 相似文献
84.
借助于Excel对物理实验数据的线性回归分析 总被引:1,自引:0,他引:1
利用Excel的强大功能,对物理实验数据进行处理、分析,对实验过种及实验结果进行监控,加强学生的计算机应用能力。本文主要应用其线性回归功能。 相似文献
85.
用相对论脉冲近似(RIA)对不同的中能质子(200MeV, 400MeV和800MeV)与14Be, 16O和12C的弹性散射进行了研究, 讨论了不同的入射能量对3种观测量, 即微分散射截面、分析本领和自旋转动函数的影响. 研究发现在小散射角的区域晕中子对观察量的影响趋势保持一致, 不随入射质子能量的改变而改变. 相似文献
86.
针对光电经纬仪嵌入式电控系统便携式调试的要求,设计了一套在线调试分析系统,上位机采用ATEML公司的哈佛处理器TSC21020-20MB为核心实现嵌入式的MCU控制系统,下位机由美国Silicon Laboratories公司的新一代具有USB2.0接口的C8051F340(简称F340)单片机和普通便携式计算机(简称PC)上运行的GUI程序组成在线调试分析系统。通过下位机在线或事后数据分析,实现了参数整定,协助上位机,进而实现对运动目标的监测、搜索与捕获、精确定向和稳定跟踪。为解决调试问题提供了一种全新的思路和新颖的方法。 相似文献
87.
A.K. Basak P.K. Roy S. Hossain M.N.A. Abdullah A.S.B. Tariq M.A. Uddin I. Reichstein F.B. Malik 《Physics letters. [Part B]》2010
Experimental cross section (CS) and vector analyzing power (VAP) data of the 6Li–28Si elastic scattering at 22.8 MeV are analyzed in the coupled-channels (CC) and coupled discretized continuum channels (CDCC) methods. Non-monotonic (NM) 6Li and α potentials of microscopic origin are employed, respectively, in the CC calculations and to generate folding potentials for the CDCC calculations. The study demonstrates that the use of central NM potentials can generate an appropriate dynamic polarization potential (DPP) required to describe both the CS and VAP data without the necessity of renormalization. This also produces an effective spin–orbit (SO) potential to account for the iT11 data without the requirement of an additional static SO potential at the incident energy considered. 相似文献