Multichannel interaction mechanism in a molecule-metal interface

Using first-principles density functional theory calculations, we reveal that the nature of the PTCDA and Ag(111) interface is characterized by multichannel molecular orbital interactions. The interacting channels via the occupied electronic states are primarily located at the periphery of PTCDA, whereas those via the unoccupied states are at the center of PTCDA. Our theory provides a unified picture explaining all the exciting experiments. Also, a confined two-dimensional free-electron-like interface state is discussed.