Optical Properties of Au Nanoclusters from TD-DFT Calculations
Optical Properties of Au Nanoclusters from TD-DFT Calculations
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DOI：
10.1021/jp112217g
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发表时间：
2011-04-14
影响因子：
3.7
通讯作者：
Stener, Mauro
中科院分区：
文献类型：
--
作者：
Durante, Nicola;Fortunelli, Alessandro;Stener, Mauro
本文采用含时密度泛函理论（TD-DFT）方法研究了N = 150个原子左右的Au纳米团簇的光学响应随以下因素的变化：（a）DFT交换相关（xc-）泛函的近似，（B）纳米团簇的形状。局域密度近似（LDA）和货车Leeuwen-Baerends（LB 94）xc-泛函的结果进行了比较的一组4个结构的图案：八面体（N = 146），立方八面体（N = 147），二十面体（N = 147），立方（N = 172），在金属纳米团簇的研究中经常遇到的结晶和非结晶图案的代表。发现光吸收谱中峰的位置与团簇的形状关系不大，但与团簇的大小和计算中所用的DFT xc-泛函密切相关，发现LB 94 xc-泛函的预测与关于Au颗粒在该尺寸范围内的吸收光谱的可用实验数据相比，相对于LDA xc-泛函的预测更好。不降低团簇的详细形状以吸收光谱的形式变得明显，其可以是对称的或不对称的两种不同形式。
A time-dependent density-functional-theory (TD-DFT) approach is employed to investigate theoretically the optical response of Au nanoclusters of size around N = 150 atoms as a function of: (a) the approximation used for the DFT exchange-correlation (xc-) functional, (b) the shape of the nanocluster. The results of the locals-density-approximation (LDA) and the van Leeuwen-Baerends (LB94) xc-functionals are compared on a set of 4 structural motifs: octahedral (N = 146), cuboctahedral (N = 147), icosahedral = 147), and cubic (N = 172), representative of both crystalline and noncrystalline motifs commonly encountered in the study of metal nanoclusters. It is found that the position of the peak in the photoabsorption spectrum is weakly dependent on the shape of the cluster but is strictly related to its size and to the DFT xc-functional used in the calculations, with the finding that the predictions of the LB94 xc-functional compare better with the available experimental data on the absorption spectrum of Au particles in this size range with respect to those of the LDA xc-functional. The detailed shape of the cluster becomes apparent in the form of the absorption spectrum, which can be symmetric or asymmetric in two different forms.