2007/03/05 by C. M. Finch, Christopher Martin Finch, Skon Sirichantaropass +9
Chemistry · Engineering · Physics and Astronomy · #Atom (system on chip) #Chemical physics #Chemistry #Condensed matter physics #Conductance #Electron #Fermi level #Force Microscopy Techniques and Applications #Geometry #HOMO/LUMO #Molecular Junctions and Nanostructures #Molecular geometry #Molecular orbital #Molecular physics #Molecule #Organic Electronics and Photovoltaics #Physics #Quantum mechanics #Twist #cond-mat.mtrl-sci
paper · pdf · doi:10.1088/0953-8984/20/02/022203
published as Journal of Physics: Condensed Matter 20, 022203 (2008) · 4 pages, 4 figures, 1 table
arxiv created 2007/03/05 · openalex publication_date 2007/12/06 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Recent experiments by Venkataraman et al (2006 Nature 442 904) on a series of molecular wires with varying chemical compositions revealed a linear dependence of the conductance on cos 2 θ, where θ is the angle of twist between neighbouring aromatic rings. To investigate whether or not this dependence has a more general applicability, we present a first-principles theoretical study of the transport properties of this family of molecules as a function of the chemical composition, conformation and the contact atom and geometry. If the Fermi energy E F lies within the HOMO–LUMO (highest occupied molecular orbital–lowest unoccupied molecular orbital) gap, then we reproduce the above experimental results. More generally, however, if E F is located within either the LUMO or the HOMO states, the presence of resonances destroys the linear dependence of the conductance on cos 2 θ and gives rise to non-monotonic behaviour associated with the level structure of the different molecules. Our results suggest that the above experiments provide a novel method for extracting spectroscopic information about molecules contacted to electrodes.