Analysis of Bonding between Conjugated Organic Molecules and Noble Metal Surfaces Using Orbital Overlap Populations.
The electronic structure of metal-organic interfaces is of paramount importance for the properties of organic electronic and single-molecule devices. Here, we use so-called orbital overlap populations derived from slab-type band-structure calculations to analyze the covalent contribution to the bonding between an adsorbate layer and a metal. Using two prototypical molecules, the strong acceptor 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) on Ag(111) and the strong donor 1H,1'H-[4,4']bipyridinylidene (HV0) on Au(111), we present overlap populations as particularly versatile tools for describing the metal-organic interaction. Going beyond traditional approaches, in which overlap populations are represented in an atomic orbital basis, we also explore the use of a molecular orbital basis to gain significant additional insight. On the basis of the derived quantities, it is possible to identify the parts of the molecules responsible for the bonding and to analyze which of the molecular orbitals and metal bands most strongly contribute to the interaction and where on the energy scale they interact in bonding or antibonding fashion.
Institut für Festkörperphysik, Technische Universität Graz, Petersgasse 16, A-8010 Graz, Austria, Department Materialphysik, Montanuniversität Leoben, Franz-Josef-Strasse 18, A-8700 Leoben, Austria, Institut für Physik, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 6, D-12489 Berlin, Germany, and Institut für Physik, Karl Franzens Universität Graz, Universitätsplatz 5, A-8010 Graz, Austria.
Gerold M
GM
Rangger
Lorenz
L
Romaner
Oliver T
OT
Hofmann
Georg
G
Heimel
Michael G
MG
Ramsey
Egbert
E
Zojer