Manifestation of Quantum Mechanical Unfurling in Transport through Single Molecule Junctions

Physical and Analytical Chemistry Seminar

Lecturer: Michael Iv

07-07 Mar 2017 @ 15:30

Location: Faculty Seminar Room

A new thermally activated ballistic transport mechanism, named Quantum Mechanical Unfurling, was recently proposed in order to explain distance independent charge transport rate in highly ordered poly-Adenine DNA sequences 3’-C(A)NCCC-5’) [1]. In this work this mechanism is examined in a molecular junction scenario, where the molecular hole transfer process is coupled to a thermal environment and to Fermion reservoirs. A minimal model approach was applied in order to capture the dynamics of hole transport through a single poly-A DNA molecule, modeled as a Donor-Bridge-Acceptor system. A kinetic scheme for the charge transport and energy distribution inside the molecule under a bias potential has been developed and analyzed.

The model calculations suggest a new manifestation of Quantum Mechanical Unfurling in single molecule junctions, where the current increases with the length of the molecular bridge. Such unusual behavior was recently observed experimentally in the (coherent) ballistic transport regime, and was attributed to delocalization of charges inside an ordered molecular bridge [2]. Here, it predicted to be observed for thermally activated (incoherent) transport through ordered molecular bridges.

Our analysis of the non-equilibrium steady state currents reveals the presence of subspaces in the molecular Fock space, associated with groups of quasi-thermalized states. The existence of these “Boltzmannized sub-spaces” can be utilized in new algorithms that overcome the exponential growth of the computational effort in simulations of transport through molecular bridge with increasing lengths.


[1] Levine, Ariel D., Michael Iv, and Uri Peskin. “Length-independent transport rates in biomolecules by   quantum mechanical unfurling.” Chemical Science 7.2 (2016): 1535-1542.

[2] Yelin, T., Korytár, R., Sukenik, N., Vardimon, R., Kumar, B., Nuckolls, C., … & Tal, O. (2016). Conductance saturation in a series of highly transmitting molecular junctions. Nature materials, 15(4), 444-449.