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重叠紧束缚模型中的光学矩阵元

Optical matrix elements in tight-binding models with overlap

Titus Sandu

摘要:

我们研究了经验紧束缚模型中轨道重叠对光学矩阵元的影响。经验紧束缚模型假设(类原子)状态的正交基和忽略原子内部分的对角坐标算子。结果表明,从一个原子的基础,这是不正交的,正交化过程中诱导的坐标算子的原子内矩阵元和扩展的有效哈密顿量的范围。我们分析了简单的紧束缚模型,表明非正交性在光学矩阵元中起着重要的作用。此外,该程序给出了Boykin [Phys. Rev \textbf{B} 57,1620(1998)]为了描述在经验紧束缚模型中被忽略的Dresselahaus项而引入的最近邻自旋轨道相互作用的形式证明。

英文摘要:

We investigate the effect of orbital overlap on optical matrix elements in empirical tight-binding models. Empirical tight-binding models assume an orthogonal basis of (atomiclike) states and a diagonal coordinate operator which neglects the intra-atomic part. It is shown that, starting with an atomic basis which is not orthogonal, the orthogonalization process induces intra-atomic matrix elements of the coordinate operator and extends the range of the effective Hamiltonian. We analyze simple tight-binding models and show that non-orthogonality plays an important role in optical matrix elements. In addition, the procedure gives formal justification to the nearest-neighbor spin-orbit interaction introduced by Boykin [Phys. Rev \textbf{B} 57, 1620 (1998)] in order to describe the Dresselahaus term which is neglected in empirical tight-binding models.

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