title: Molecular distortions and chemical bonding of a large pi-conjugated molecule on a metal surface.
abstract: Normal incidence x-ray standing wave experiments and density functional theory reveal that 3,4,9,10-perylene-tetracarboxylic-dianhydride chemisorbs on Ag(111) in a nonplanar but vertically distorted configuration. The carboxylic O atoms are 0.18 +/- 0.03 angstroms closer to the surface than the perylene core. The distortion is related to weak, local bonds between carboxylic O atoms and the Ag surface which are coupled--through charge transfer into the former lowest unoccupied molecular orbital--to the primary, extended chemisorption bond via the perylene skeleton.
authors.affiliation: Institut für Physikalische und Theoretische Chemie der Universität Bonn, Wegelerstrasse 12, 53115 Bonn, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Hauschild
authors.forename: K
authors.initials: K
authors.lastname: Karki
authors.forename: B C C
authors.initials: BC
authors.lastname: Cowie
authors.forename: M
authors.initials: M
authors.lastname: Rohlfing
authors.forename: F S
authors.initials: FS
authors.lastname: Tautz
authors.forename: M
authors.initials: M
authors.lastname: Sokolowski