Single and double valence configuration interactions for recovering the exponential decay law while tunneling through a molecular wire

Abstract

The exponential decay of the electronic transmission through a molecular wire with its length is calculated using a configuration interaction elastic scattering quantum chemistry (CI-ESQC) theory [, ]. In the HOMO–LUMO gap and in a one-electron approximation, this decay is exponential since the scattering matrix comes from a product of spatial propagators along the wire. In a valence SD–CI (single and double-configurations interaction) description, such a product does not exist. An effective one was numerically obtained from the CI-ESQC scattering matrix. Fluctuations over the effective CI-exponential decay come from the truncation of the full CI basis set and also from many-body exchange-correlation effects along the molecular wire.