19 research outputs found
Modeling transport through single-molecule junctions
Non-equilibrium Green's functions (NEGF) formalism combined with extended
Huckel (EHT) and charging model are used to study electrical conduction through
single-molecule junctions. Analyzed molecular complex is composed of asymmetric
1,4-Bis((2'-para-mercaptophenyl)-ethinyl)-2-acetyl-amino-5-nitro-benzene
molecule symmetrically coupled to two gold electrodes [Reichert et al., Phys.
Rev. Lett. Vol.88 (2002), pp. 176804]. Owing to this model, the accurate values
of the current flowing through such junction can be obtained by utilizing basic
fundamentals and coherently deriving model parameters. Furthermore, the
influence of the charging effect on the transport characteristics is
emphasized. In particular, charging-induced reduction of conductance gap,
charging-induced rectification effect and charging-generated negative value of
the second derivative of the current with respect to voltage are observed and
examined for molecular complex.Comment: 8 pages, 3 figure
The Role of Bound States in Time-Dependent Quantum Transport
Charge transport through a nanoscale junction coupled to two macroscopic
electrodes is investigated for the situation when bound states are present. We
provide numerical evidence that bound states give rise to persistent,
non-decaying current oscillations in the junction. We also show that the
amplitude of these oscillations can exhibit a strong dependence on the history
of the applied potential as well as on the initial equilibrium configuration.
Our simulations allow for a quantitative investigation of several transient
features. We also discuss the existence of different time-scales and address
their microscopic origin.Comment: 10 pages, 8 figure