title: Structural evolution of anionic silicon clusters SiN (20 <or= N <or= 45).
abstract: Results of a combined photoelectron spectroscopy and first-principles density-functional study of SiN- clusters in the size range 20 <or= N <or= 45 are reported and discussed. Evidence for a prolate-to-near-spherical shape transition at N = 27 is presented. It is shown that the tricapped-trigonal-prism (TTP) structural motif Si9 found in most low-lying clusters SiN-, 9 <or= N <or= 19, is replaced or augmented by a series of structural motifs consisting of a bulklike "adamantane" fragment plus a magic-number cluster (Si6, Si7, Si10) or TTP Si9 in low-lying prolate clusters SiN-, N >or= 20. For 28 <or= N <or= 45, almost all low-lying near-spherical clusters SiN- adopt "stuffed-cage"-like structures where the cages are homologous to carbon fullerenes in the sense that they are composed of only five- and six-membered rings. However the arrangement of the "stuffing" atoms is not yet diamondlike.
authors.affiliation: Department of Chemistry and Center for Materials Research & Analysis, University of Nebraska, Lincoln, Nebraska 68588, USA.
authors.forename: Jaeil
authors.initials: J
authors.lastname: Bai
authors.forename: Li-Feng
authors.initials: LF
authors.lastname: Cui
authors.forename: Jinlan
authors.initials: J
authors.lastname: Wang
authors.forename: Soohaeng
authors.initials: S
authors.lastname: Yoo
authors.forename: Xi
authors.initials: X
authors.lastname: Li
authors.forename: Julius
authors.initials: J
authors.lastname: Jellinek
authors.forename: Christof
authors.initials: C
authors.lastname: Koehler
authors.forename: Thomas
authors.initials: T
authors.lastname: Frauenheim
authors.forename: Lai-Sheng
authors.initials: LS
authors.lastname: Wang
authors.forename: Xiao Cheng
authors.initials: XC
authors.lastname: Zeng