Cluster-based density-functional approach to quantum transport through molecular and atomic contacts

Abstract

We present a cluster-based approach to model charge transport through molecular and atomic contacts. The electronic structure of the contacts is determined in the framework of density functional theory, and the parameters needed to describe transport are extracted from finite clusters. A similar procedure, restricted to nearest-neighbor interactions in the electrodes, has been presented by Damle et al (2002 Chem. Phys. 281 171). Here, we show how to systematically improve the description of the electrodes by extracting bulk parameters from sufficiently large metal clusters. In this way, we avoid problems arising from the use of nonorthogonal basis functions. For demonstration, we apply our method to electron transport through Au contacts with various atomic-chain configurations and to a single-atom contact of Al.