Interface Characteristics at an Organic/Metal Junction: Pentacene on Cu Stepped Surfaces

Abstract

The adsorption of pentacene on Cu(221), Cu(511) and Cu(911) is investigated using density functional theory (DFT) with the self-consistent inclusion of van der Waals (vdW) interactions. Cu(211) is a vicinal of Cu(111) while Cu(511) and (911) are vicinals of Cu(100). For all the three surfaces, we found pentacene to prefer to adsorb parallel to the surface and near the steps. The addition of vdW interactions resulted in an enhancement in adsorption energies, with reference to the PBE functional, of around 2 eV. With vdWs inclusion, the adsorption energies were found to be 2.98 eV, 3.20 eV and 3.49 eV for Cu(211), Cu(511) and Cu(911) respectively. These values reflect that pentacene adsorbs stronger on (100) terraces with a preference for larger terraces. The molecule tilts upon adsorption with a small tilt angle on the (100) vicinals (about a few degrees) as compared to a large one on Cu(221) where the tilt angle is found to be about 20o. We find that the adsorption results in a net charge transfer to the molecule of ~1 electron, for all surfaces.

arXiv comment11 pages, 4 figures

References in corpus (9)

• Van der Waals Density Functional for General Geometries
• Van der Waals density functionals applied to solids
• Accurate and efficient algorithm for Bader charge integration
• Van der Waals density functional: Self-consistent potential and the nature of the van der Waals bond
• Benzene Adsorbed on Metals: Concerted Effect of Covalency and van der Waals Bonding
• Insight into the description of van der Waals forces for benzene adsorption on transition metal (111) surfaces
• Evaluation of New Density Functional with Account of van der Waals Forces by Use of Experimental H2 Physisorption Data on Cu(111)
• Ab initio Calculations of Multilayer Relaxations of Stepped Cu Surfaces
• A comparative study of the energetics of CO on stepped and kinked Cu surfaces using density functional theory