Equiconducting molecular electronic devices

For molecular conductors, the source-sink potential (SSP) model provides a simple tool for the calculation of the electron transmission probability. Recently, the SSP method has been combined with graph theory, and criteria have been established under which two different molecular electronic devices yield identical transmission probabilities. Since these criteria have been arrived at within the Huumlckel approximation, we investigate the validity of these criteria by performing combined Kohn-Sham and Green's function calculations for the transmission probability. We find that some systems, predicted to be equiconducting at the Huumlckel level, are approximately equiconducting at the nonempirical level while others are not. An explanation for the obtained discrepancies is proposed.