Evolution of atomic structures of Sn<i>N</i>, Sn<i>N</i>−, and Sn<i>N</i>Cl− clusters (<i>N</i> = 4–20): Insight from <i>ab initio</i> calculations

Abstract

An unbiased global search was employed to explore the low-energy structures of Sn_N, Sn_N ^-, and Sn_NCl^- clusters with N = 4-20 atoms based on the genetic algorithm combined with density functional theory calculations. Some unprecedented low-energy isomers are reported for Sn_N and Sn_NCl^- clusters. The theoretical electronic properties such as binding energy per atom, ionization potential, adiabatic detachment energy, and vertical detachment energy compare well with the experimental data. Based on the equilibrium structures, the simulated photoelectron spectra are in good agreement with the experimental data in the range of N = 4-20. With addition of a Cl atom on the Sn_N ^- cluster, which causes almost no rearrangement on the structural framework, the first peaks in all original photoelectron spectra of Sn_N ^- clusters disappear and other peaks nearly retain the original feature at most sizes.