中国物理B ›› 2007, Vol. 16 ›› Issue (3): 700-706.doi: 10.1088/1009-1963/16/3/024
白玉林1, 程晓洪1, 杨向东2, 陈向荣3
Bai Yu-Lin(白玉林)a), Chen Xiang-Rong(陈向荣)b)† , Cheng Xiao-Hong(程晓洪)a), and Yang Xiang-Dong(杨向东)a)b)
摘要: Absorption spectra for S2 clusters (n=2\ldots8) are calculated using an adiabatic time-dependent density functional formalism within the local density approximation (LDA). We compare the calculated spectra with those computed using a simple LDA approach. The time-dependent LDA (TDLDA) spectra display a significant blue shift with respect to the LDA spectra. The calculated spectra present a variety of features that can be used for comparison with future experimental investigations. We also obtain a significant threshold absorption, which can distinguish between different ground states of the sulfur clusters. In addition, the polarizabilities of the clusters are calculated by using the higher-order finite-difference pseudopotential density functional method in real space. We find that the polarizabilities of the clusters considered are higher than the value estimated from the `hard sphere' model using the bulk static dielectric constant. The computed polarizabilities per atom tend to decrease with increasing cluster size. The polarizabilities are closely related to the HOMO--LUMO gaps and the geometrical configurations.
中图分类号: (Ab initio calculations)