Ab initio study of pentacene on Au(0Â 0Â 1) 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(0 0 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 [1 1 0] 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.