title: Planar-to-tubular structural transition in boron clusters: B20 as the embryo of single-walled boron nanotubes.
abstract: Experimental and computational simulations revealed that boron clusters, which favor planar (2D) structures up to 18 atoms, prefer 3D structures beginning at 20 atoms. Using global optimization methods, we found that the B20 neutral cluster has a double-ring tubular structure with a diameter of 5.2 A. For the B(-)20 anion, the tubular structure is shown to be isoenergetic to 2D structures, which were observed and confirmed by photoelectron spectroscopy. The 2D-to-3D structural transition observed at B20, reminiscent of the ring-to-fullerene transition at C20 in carbon clusters, suggests it may be considered as the embryo of the thinnest single-walled boron nanotubes.
authors.affiliation: Department of Physics, Washington State University, 2710 University Drive, Richland, WA 99352, USA.
authors.forename: Boggavarapu
authors.initials: B
authors.lastname: Kiran
authors.forename: Satya
authors.initials: S
authors.lastname: Bulusu
authors.forename: Hua-Jin
authors.initials: HJ
authors.lastname: Zhai
authors.forename: Soohaeng
authors.initials: S
authors.lastname: Yoo
authors.forename: Xiao Cheng
authors.initials: XC
authors.lastname: Zeng
authors.forename: Lai-Sheng
authors.initials: LS
authors.lastname: Wang