G3理论研究Si_nNa(n=2-7)团簇的结构和电子亲合能

A STUDY ON STRUCTURES AND ELECTRON AFFINITIES OF Si_nNa (n=2-7) UPON GAUSSIAN-3 THEORY

采用Gaussian-3(G3)理论方法对SinNa(n=2-7)体系进行了系统的研究,分别计算了它们的基态结构和电子亲合能。结果表明SinNa中性分子的基态结构是"吸附结构",即Na原子吸附在Sin团簇的表面;SinNa-阴离子的基态结构是"取代结构",即Na原子取代Sin+1团簇中的一个硅原子;在电子亲合能方面,预测Si2Na、Si3Na、Si4Na、Si5Na、Si6Na和Si7Na的电子亲合能分别是1.74、1.88、1.65、2.40、2.01和1.95 eV。除此之外,还计算了Na原子从SinNa和SinNa-基态结构中分裂出来的分裂能,并讨论了它们的相对稳定性。

The molecular structures of neutral SinNa（n=2-7） species and their anions have been studied by means of G3 techniques.The lowest energy structures of these clusters and their electron affinities are calculated.The ground-state structures of neutral SinNa are ＂attaching structures＂,in which the Na atom is bonded to Sin clusters.The ground-state structures of anions,however,are ＂substitutional structures＂,that is,in Sin＋1 clusters,a Si atom is substituted with a Na atom.The predicted electron affinities of SinNa are,respectively,1.74 eV for Si2Na,1.88 eV for Si3Na,1.65 eV for Si4Na,2.40 eV for Si5Na,2.01 eV for Si6Na and 1.95 eV for Si7Na.Dissociation energies of the Na atom,dissociated from the lowest energy structures of SinNa and SinNa-,have also been estimated.Their relative stabilities are discussed.