含时密度泛函理论研究氢化硅小团簇的光吸收谱
Photo-absorption spectra of small hydrogenated silicon clusters using the time-dependent density functional theory
摘要：
本文用含时密度泛函理论（TDDFT）研究了Si $_{n}$ H $_{m}$团簇（n=1-10，m=1-14）的光吸收谱.该方法使用的TDDFT涉及时间相关的Kohn-Sham方程的全传播的实时，实空间实现。我们对SiH $_{4}$和Si $_{2}$ H $_{6}$的计算结果与以前的计算和实验数据吻合得很好。我们发现，对于小团簇（n<7）的光吸收光谱是原子状的，而对于较大的团簇，它表现出块状的行为。我们研究了硅团簇的光吸收光谱作为氢化的函数。对于单氢化，我们发现，在一般情况下，吸收光学带隙减小，随着硅原子的数目增加，单个氢原子的光学带隙的影响减小。对于进一步氢化的光学带隙增加，并且对于完全氢化的团簇，光学带隙与相应的纯硅团簇相比更大。
英文摘要：
We present a systematic study of the photo-absorption spectra of various Si$_{n}$H$_{m}$ clusters (n=1-10, m=1-14) using the time-dependent density functional theory (TDDFT). The method uses a real-time, real-space implementation of TDDFT involving full propagation of the time dependent Kohn-Sham equations. Our results for SiH$_{4}$ and Si$_{2}$H$_{6}$ show good agreement with the earlier calculations and experimental data. We find that for small clusters (n<7) the photo-absorption spectrum is atomic-like while for the larger clusters it shows bulk-like behaviour. We study the photo-absorption spectra of silicon clusters as a function of hydrogenation. For single hydrogenation, we find that in general, the absorption optical gap decreases and as the number of silicon atoms increase the effect of a single hydrogen atom on the optical gap diminishes. For further hydrogenation the optical gap increases and for the fully hydrogenated clusters the optical gap is larger compared to corresponding pure silicon clusters.
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