Organic/metal interfaces: an ab initio study of their structural and electronic properties

By means of ab initio calculations, we present a theoretical study of Pd porphyrin deposited on an Al(1 1 1) metallic substrate, focusing on the interaction between molecules and metal surfaces and on the alignment of molecular levels at the interface. The changes induced on the relevant electronic properties by the use of a different parametrization (i.e. local density approximation vs generalized gradient approximation) of the exchange-and-correlation potential within the density functional theory are discussed. The results show that the molecule–substrate interaction is rather weak and that the character of the contact is rectifying.