Ab initio calculations for the absorption spectra and polarizabilities of small sulfur clusters  

作　　者：白玉林 陈向荣 程晓洪 杨向东 

机构地区：[1]Department of Physics and Electronic Information, Yibin University, Yibin 644000, China [2]Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China

出　　处：《Chinese Physics B》2007年第3期700-706,共7页中国物理B（英文版）

基　　金：Project supported by the National Natural Science Foundation of China （Grant No 10274055）, the Natural Science Foundation of Sichuan Education Bureau, China （Grant No 2004A181） and the Research Fund for the Doctoral Program of Yibin University, China （Grant No 2005B01）.

摘　　要：Absorption spectra for Sn clusters （n=2...8） 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 higherorder 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.Absorption spectra for Sn clusters （n=2...8） 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 higherorder 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.

关 键 词：absorption spectra threshold absorption POLARIZABILITY HOMO-LUMO gaps 

分 类 号：O561[理学—原子与分子物理] O562.3[理学—物理]