The role of the tip symmetry on the STM topography of ‐conjugated molecules

Abstract

We present an STM theory based on the reduced density matrix (RDM) formalism which is able to describe transport properties of an STM junction for ‐conjugated molecules on thin insulating films. It combines a very popular derivation of STM tunneling matrix elements (), based on Bardeen's tunneling formalism (), with a generalized master equation approach for interacting molecular systems. We show that this method allows the efficient implementation of different tip symmetries in STM simulations. With the example of hydrogen phthalocyanine (H2 Pc), we study the influence of s‐ and p‐wave tip symmetries on the constant‐height current maps of ‐conjugated molecules. Constant‐height STM images evaluated at the cationic resonance of H2 Pc. Left image computed by using an s‐wave tip and right image for a linear combination of px and py states.