title: Dynamical behavior of boron clusters.
abstract: Several of the lowest energy structures of small and medium sized boron clusters are two-dimensional systems made up of a pair of concentric rings. In some cases, the barriers to the rotation of one of those rings relative to the other are remarkably low. We find that a combination of electronic and geometrical factors, including apparently the relative sizes and symmetries of the inner and outer rings, are decisive for the diminished barriers to in-plane rotation in these two dimensional clusters. A sufficiently large outer ring is important; for instance, expansion of the outer ring by a single atom may reduce the barrier significantly. A crucial factor for an apparent rotation is that the σ-skeleton of the individual rings remains essentially intact during the rotation. Finally, the transition state for the rotation of the inner ring comprises the transformation of a square into a diamond, which may be linked to a mechanism suggested decades ago for the isomerization of carboranes and boranes.
authors.affiliation: Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados, 97310 Mérida, Yucatán, Mexico. gmerino@cinvestav.mx.
authors.forename: Said
authors.initials: S
authors.lastname: Jalife
authors.affiliation: Mulliken Center for Theoretical Chemistry, Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115 Bonn, Germany.
authors.forename: Lei
authors.initials: L
authors.lastname: Liu
authors.affiliation: Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados, 97310 Mérida, Yucatán, Mexico. gmerino@cinvestav.mx.
authors.forename: Sudip
authors.initials: S
authors.lastname: Pan
authors.affiliation: Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados, 97310 Mérida, Yucatán, Mexico. gmerino@cinvestav.mx.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Cabellos
authors.affiliation: Departamento de Ciencias Básicas. Fundación Universitaria Luis Amigó, SISCO, Transversal 51A # 67B 90, Medellín, Colombia.
authors.forename: Edison
authors.initials: E
authors.lastname: Osorio
authors.affiliation: Department of Physics, Nanyang Normal University, Nanyang 473061, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Lu
authors.affiliation: Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstr 2, D-04103, Leipzig, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Heine
authors.affiliation: Department of Chemistry, Gottwald Center for the Sciences, University of Richmond, Richmond, Virginia 23173, USA. kdonald@richmond.edu.
authors.forename: Kelling J
authors.initials: KJ
authors.lastname: Donald
authors.affiliation: Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados, 97310 Mérida, Yucatán, Mexico. gmerino@cinvestav.mx.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Merino