Scanning tunneling microscopy simulations of poly(3-dodecylthiophene) chains adsorbed on highly oriented pyrolytic graphite

摘要

We report on a novel scheme to perform efficient simulations of ScanningTunneling Microscopy (STM) of molecules weakly bonded to surfaces. Calculationsare based on a tight binding (TB) technique including self-consistency for themolecule to predict STM imaging and spectroscopy. To palliate the lack ofself-consistency in the tunneling current calculation, we performed firstprinciples density-functional calculations to extract the geometrical andelectronic properties of the system. In this way, we can include, in the TBscheme, the effects of structural relaxation upon adsorption on the electronicstructure of the molecule. This approach is applied to the study ofregioregular poly(3-dodecylthiophene) (P3DDT) polymer chains adsorbed on highlyoriented pyrolytic graphite (HOPG). Results of spectroscopic calculations arediscussed and compared with recently obtained experimental dat