Using a technique based on embedding in a local-orbital formalism, the electronic structure and electron transmission properties of long biological molecules may be calculated. The electronic structure is found by adding one structural unit at a time to the molecule, and calculating an embedding potential for adding the next structural unit. At present an extended Hückel scheme is used to evaluate the matrix elements. The transmission is also calculated within the embedding scheme, taking the molecule-metal contacts into account. Results for the density of states and transmission are presented for several structures of DNA. The transmission is highly energy dependent, and is also greatly influenced by the orbitals to which contact is made. The implications of these calculations for conductance are discussed.

• Received 20 August 2003

DOI:https://doi.org/10.1103/PhysRevB.69.195110