Abstract
We have studied the electronic structure of pentacene adsorbed on Cu(111) using density functional theory (DFT) within a generalized gradient approximation (GGA), to investigate the origin of the surface-band dispersion. We show that the surface-band dispersion at the pentacene/Cu(111) interface is well reproduced by using theoretically optimized adsorption geometry. The dispersion is attributed to the hybridization of pentacene lowest unoccupied molecular orbital (LUMO) with the substrate d states, which varies depending on the wave vector, suggesting the important role of the chemical interaction at this interface.