▎ 摘　　要

We perform ab initio calculations of electronic and transport properties of nanoelectronic systems. The surface Green's function of semi-infinite ribbons made from graphene sheets is constructed from ab initio one-dimensional bulk calculations, and the energy dependent transmission coefficient through a molecular tunneling junction is computed from Landauer's formalism within a framework that combines Caroli's approach and density functional theory. By using the same level of theory and basis set to model both the molecule and the ribbons, and by an exact, analytical determination of surface Green's functions, we aim for a quantitative description of the configuration dependent electron transport through ribbon-molecule-ribbon switching devices.