title: Evolution of the Structural and Electronic Properties of Medium-Sized Sodium Clusters: A Honeycomb-Like Na20Cluster.
abstract: Sodium is one of the best examples of a free-electron-like metal and of a certain technological interest. However, an unambiguous determination of the structural evolution of sodium clusters is challenging. Here, we performed an unbiased structure search among neutral and anionic sodium clusters in the medium size range of 10-25 atoms, using the Crystal structure AnaLYsis by Particle Swarm Optimization (CALYPSO) method. Geometries are determined by CALYPSO structure searches, followed by reoptimization of a large number of candidate structures. For most cluster sizes the simulated photoelectron spectra of the lowest-energy structures are in excellent agreement with the experimental data, indicating that the current ground-state structures are the true minima. The equilibrium geometries show that, for both neutral and anionic species, the structural evolution from bilayer structures to layered outsides with interior atoms occurs at n = 16. A novel unprecedented honeycomb-like structure of Na20cluster with C3symmetry is uncovered, which is more stable than the prior suggested structure based on pentagonal structural motifs.
authors.affiliation: Institute of Atomic and Molecular Physics, Sichuan University , Chengdu 610065, China.|Department of Physics, Nanyang Normal University , Nanyang 473061, China.
authors.forename: Wei Guo
authors.initials: WG
authors.lastname: Sun
authors.affiliation: Institute of Atomic and Molecular Physics, Sichuan University , Chengdu 610065, China.|Education College of Information Technology, Hubei Nomal University , Huangshi 435002, China.
authors.forename: Jing Jing
authors.initials: JJ
authors.lastname: Wang
authors.affiliation: Department of Physics, Nanyang Normal University , Nanyang 473061, China.|Department of Physics and High Pressure Science and Engineering Center, University of Nevada , Las Vegas, Nevada 89154, United States.
authors.forename: Cheng
authors.identifier: http://orcid.org/0000-0003-1746-7697
authors.initials: C
authors.lastname: Lu
authors.affiliation: Institute of Atomic and Molecular Physics, Sichuan University , Chengdu 610065, China.
authors.forename: Xin Xin
authors.initials: XX
authors.lastname: Xia
authors.affiliation: Institute of Atomic and Molecular Physics, Sichuan University , Chengdu 610065, China.
authors.forename: Xiao Yu
authors.initials: XY
authors.lastname: Kuang
authors.affiliation: Centre for Science at Extreme Conditions and SUPA, School of Physics and Astronomy, The University of Edinburgh , Edinburgh EH9 3JZ, United Kingdom.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hermann