Structural, Electronic and Optical Properties of Medium Sized Neutral and Cationic Li_(n) Cluster (n(velence)2, 8 10 20, 30) by Density Functional Theory

摘要

Structure, stability and electronic properties of medium sized neutral and cationic lithium clusters Li_(n) (n(velence)2, 8, 10, 20, 30) have been investigated within the framework of Density -Functional Theory at B3LYP level using 6-311G~(*) basis se. The results show that cationic clusters are energetically favorable compared to neutral ones. At magic-number sizes (n(velence)2, 8, 10, 20), Li_(n) clusters posses relatively large HOMO-LUMO gaps and higher ionization potentials, corresponding to closure of the electronic shell. For Li_(20) all three diagonal elements of the polarizability tensor are equal ((alpha)_(xx)velence1159.038, (alpha)_(yy)velence1171.054, (alpha)_(zz)velence1187.068) and found to be significantly isotropic. The structure of Li_(20) shows a remarkable symmetry. Whenever possible, results have been compared with available data. A good agreement between experimental and theoretical results suggests a good prediction of lowest energy structure for all clusters calculated in the present study.