2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/21972We validate that off-resonant electron transport across {\it ultra-short} oligomer molecular junctions is characterised by a conductance which decays exponentially with length, and we discuss a method to determine the damping factor via the energy spectrum of a periodic structure as a function of complex wavevector. An exact mapping to the complex wavevector is demonstrated by first-principle-based calculations of: a) the conductance of molecular junctions of phenyl-ethynylene wires covalently bonded to graphitic ribbons as a function of the bridge length, and b) the complex-band structure of poly-phenyl-ethynylene.version to appear in Chem Phys Lett; 8 pages, 4 figures; minor changes to the 06/08/03 submission (nomenclature and added concluding remark)Materials ScienceMesoscale and Nanoscale PhysicsChemical Physicstext