Lehtonen Olli, Sundholm Dage, Vänskä Tommy
Department of Chemistry, University of Helsinki (A.I. Virtasen Aukio 1), Finland.
Phys Chem Chem Phys. 2008 Aug 21;10(31):4535-50. doi: 10.1039/b804212h. Epub 2008 Jul 9.
Light-absorption and luminescence processes in nano-sized materials can be modelled either by using computational approaches developed for quantum chemical calculations or by applying computational methods in the effective mass approximation (EMA) originally intended for solid-state theory studies. An overview of the theory and implementation of an ab initio correlation EMA method for studies of luminescence properties of embedded semiconductor quantum dots is presented. The applicability of the method and the importance of correlation effects are demonstrated by calculations on InGaAs/GaAs quantum-dot and quantum-ring samples. Ab initio and density functional theory (DFT) quantum chemical studies of optical transitions in freestanding silicon nanoclusters are also discussed. The accuracy of the optical gaps and oscillator strengths for silicon nanoclusters obtained using different computational methods is addressed. Changes in the cluster structures, excitation energies and band strengths upon excitation are reported. The role of the surface termination and functional groups on the silicon nanocluster surfaces is discussed.
纳米材料中的光吸收和发光过程既可以通过使用为量子化学计算开发的计算方法来建模，也可以通过应用最初用于固态理论研究的有效质量近似（EMA）中的计算方法来建模。本文概述了一种用于研究嵌入式半导体量子点发光特性的从头算关联EMA方法的理论和实现。通过对InGaAs/GaAs量子点和量子环样品的计算，证明了该方法的适用性以及关联效应的重要性。还讨论了独立硅纳米团簇中光学跃迁的从头算和密度泛函理论（DFT）量子化学研究。探讨了使用不同计算方法获得的硅纳米团簇的光学带隙和振子强度的准确性。报告了激发时团簇结构、激发能和能带强度的变化。讨论了硅纳米团簇表面的表面终止和官能团的作用。
