COMPUTATION OF ELECTROSTATIC FIELDS IN LOW-SYMMETRY SYSTEMS - APPLICATION TO STM CONFIGURATIONS

When complex molecules are placed in interaction with a low-symmetry p hysical system, an electrostatic field confined at the nanometer scale arises in a region located around the particles. It is the case in sc anning tunneling microscopy (STM), where these long-range interactions modify the intrinsic electrostatic field structure and, thereby, affe ct the magnitude of the cohesive forces between each adsorbed particle s. We present a numerical approach of this problem within the framewor k of the held-propagator method. Starting from the knowledge of the fi eld distribution associated with a highly symmetrical system (a pair o f metallic plane electrodes, for example), we derive the self-consiste nt field distribution for the whole system by introducing a generalize d field propagator obtained by solving a sequence of Dyson's equations numerically. The application of this numerical scheme to electrostati c herd calculations inside a STM junction is studied in detail.