对全金属La_4^(2-)团簇芳香性的从头算理论研究  

Ab initio study on the aromaticity of all-metallic anion La_4^(2-)

作　　者：刘勇[1] 祁红艳[1] 罗亚文[1] 胡君[1] 黄晓明[1] 池贤兴[2] 

机构地区：[1]湖北第二师范学院物理与电子信息学院,武汉430205 [2]温州大学物理与电子信息学院,温州325027

出　　处：《原子与分子物理学报》2014年第1期66-70,共5页Journal of Atomic and Molecular Physics

基　　金：浙江省自然科学基金(102069)

摘　　要：我们将芳香性扩展到全金属阴离子团簇La2-4.运用从头算方法(B3LYP/LANL2DZ,B3PW91/LANL2DZ and MP2/LANL2DZ)进行了结构优化.计算结果显示,阴离子团簇有两个同分异构体,一个是C2v结构,另一个是正方形D4h结构.进一步对能量的分析得出,D4h结构比C2v结构更稳定.对最稳定的D4h结构计算了核独立位移(NICS),结果显示正方形的La2-4环呈现强芳香性.详细的分子轨道(Mos)分析揭示正方形的La2-4环拥有四个独立的离域化成键系统,每一个系统拥有两个电子,分别满足4n+2芳香性电子计算规则,因此呈现四重芳香性.We extended the aromaticity concept to all-metallic anion La 4 -- and then performed Ab intio calculations（B3LYP/LANL2DZ, B3PW91/LANL2DZ and MP2/LANL2DZ） on the selected structures. The computed results indicate that anion La 4 2- has two stable isomers., one is the bidentate C2v structure and another is the square planar D4h structure. The further analysis on energies shows that the square planar D4h structure is more stable than the bidentate C2v structure. The computed nucleus-independent chemical shifts（NICS） on the most stable D4h structure show that the square planar La4 2- ring exhibits higher degree of aromaticity. The detailed Mos analysis further reveals that the square planar La4 2- ring possesses four independent delocalized bonding systems, each has two electrons satisfying the 4n ＋ 2 electron counting rule of aromaticity, suggesting that these species have four-fold aromaticity.

关 键 词：从头算法 芳香性 磁化率 核独立位移 

分 类 号：O562.1[理学—原子与分子物理]