密度泛函理论研究贵金属耦合纳米团簇的静电极化率与吸收光谱  

Study on Static Polarizability and Absorption Spectrum of Coupling Noble Metal Nanoclusters by Density Functional Theory

作　　者：吴波[1,2] 杨秀德[1] 张颂[2] 

机构地区：[1]遵义师范学院物理系,遵义563002 [2]西南大学物理科学与技术学院,重庆400715

出　　处：《材料导报》2011年第20期1-6,14,共7页Materials Reports

基　　金：国家自然科学基金(50666001);遵义市科技研究发展项目(遵市科合社字[2010]08号)

摘　　要：基于密度泛函理论计算了2个贵金属(Ag、Au、Cu)纳米团簇组成的团簇对的静电极化率和吸收光谱,结果表明这2个团簇之间存在强烈的静电耦合效应,其贡献主要来自于外加弱电场下团簇之间的电荷迁移和电子云的扭曲。随着团簇对间距的不断增大,静电极化率先增大后减小,存在一个极化率最大的最佳位置。在团簇对的吸收谱中,随着团簇对间距的增加,高能峰的位置和强度基本保持不变,而低能峰则不断蓝移且峰值先增大后减小,最终消失于高能峰的位置。进一步计算团簇-吡嗪和团簇-吡嗪-团簇体系的静电极化率和吸收光谱,结果发现团簇连接有机小分子后部分电子将从有机小分子向团簇迁移,使整个体系具有较大的固有极矩,在外加弱电场下,团簇与有机小分子之间的电荷迁移能力显著增强。For a cluster-pair consisting of two same noble metal（Ag, Au, Cu） clusters, the static polarizability and absorption spectrum were calculated within density functional theory（DFT）. The results show that between two cluster particles an intense static coupling effect exist, and under weak electric field which are mainly contributed by the charge transfer between two clusters and the distortion of electron cloud of individual cluster. Increasing interval distance of cluster-pair, the polarizability increases firstly then decreases, and an optimal position is characterized by the maximal polarizability. For the absorption spectrum of the cluster-pair, with the increase of interval distance the high-energy peak almost hold its absorption position unchanged, then the low-energy peak will step blue shift and the strength increases firstly then gradually decreases, lastly disappears at the high energy position. For the static polarizability and absorption spectrum of the cluster-pyrazine or the cluster-pyrazine-cluster system, the farther calculations show that some electrons in small organic molecule will transfer into the cluster, which cause a biggish permanent dipole moment in whole particles system and result in an obvious enhancement of charge transfer between the cluster and small organic molecule under weak electric field.

关 键 词：极化率 吸收光谱 密度泛函理论 耦合效应 

分 类 号：O561[理学—原子与分子物理]