Ab initio study of pentacene on Au(001) surface

We report results of our first-principles density-functional studies on the nature of intermolecular interactions between pentacene (C22H14) molecules and adsorption properties of the molecule on Au(00 1) surface. The energetics and electronic structure of two pentacene molecules in various configurations show an anisotropic nature of intermolecular interactions between the molecules. From total energy calculations, it is predicted that a single pentacene molecule adsorbed on Au(0 0 1) surface prefer to be centered at the bridge site, aligning its long-axis to the [I 10] direction of the Au(0 0 1) substrate. The structural distortions of the adsorbed molecule are closely related to the orbital characteristics of the HOMO and LUMO states and indicate a possible back-donation from the metal substrate to the molecule. (c) 2005 Elsevier B.V. All rights reserved.