4 research outputs found
First-principles study of phenyl ethylene oligomers as current-switch
We use a self-consistent method to study the distinct current-switch of
-amino-4-ethynylphenyl-4'-ethynylphenyl-5'-nitro-1-benzenethiol, from
the first-principles calculations. The numerical results are in accord with the
early experiment [Reed et al., Sci. Am. \textbf{282}, 86 (2000)]. To further
investigate the transport mechanism, we calculate the switching behavior of
p-terphenyl with the rotations of the middle ring as well. We also study the
effect of hydrogen atom substituting one ending sulfur atom on the transport
and find that the asymmetry of I-V curves appears and the switch effect still
lies in both the positive and negative bias range.Comment: 6 pages, 6 figure
Ab initio study of single molecular transistor modulated by gate-bias
We use a self-consistent method to study the current of the single molecular
transistor modulated by the transverse gate-bias in the level of the
first-principles calculations. The numerical results show that both the
polyacene-dithiol molecules and the fused-ring oligothiophene molecules are the
potential high-frequency molecular transistor controlled by the transverse
field. The long molecules of the polyacene-dithiol or the fused-ring thiophene
are in favor of realizing the gate-bias controlled molecular transistor. The
theoretical results suggest the related experiments.Comment: 14 pages, 7 figure
Density functional calculations of nanoscale conductance
Density functional calculations for the electronic conductance of single
molecules are now common. We examine the methodology from a rigorous point of
view, discussing where it can be expected to work, and where it should fail.
When molecules are weakly coupled to leads, local and gradient-corrected
approximations fail, as the Kohn-Sham levels are misaligned. In the weak bias
regime, XC corrections to the current are missed by the standard methodology.
For finite bias, a new methodology for performing calculations can be
rigorously derived using an extension of time-dependent current density
functional theory from the Schroedinger equation to a Master equation.Comment: topical review, 28 pages, updated version with some revision