169 research outputs found
Transport of overdamped Brownian particles in a two-dimensional tube: Nonadiabatic regime
Transport of overdamped Brownian particles in a two-dimensional asymmetric
tube is investigated in the presence of nonadiabatic periodic driving forces.
By using Brownian dynamics simulations we can find that the phenomena in
nonadiabatic regime differ from that in adiabatic case. The direction of the
current can be reversed by tuning the driving frequency. Remarkably, the
current as a function of the driving amplitude exhibits several local maxima at
finite driving frequency.Comment: 10 pages, 4 figure
A channel Brownian pump powered by an unbiased external force
A Brownian pump of particles in an asymmetric finite tube is investigated in
the presence of an unbiased external force. The pumping system is bounded by
two particle reservoirs. It is found that the particles can be pumped through
the tube from a reservoir at low concentration to one at the same or higher
concentration. There exists an optimized value of temperature (or the amplitude
of the external force) at which the pumping capacity takes its maximum value.
The pumping capacity decreases with increasing the radius at the bottleneck of
the tube.Comment: 14 pages, 9 figure
Complex quantum network model of energy transfer in photosynthetic complexes
The quantum network model with real variables is usually used to describe the
excitation energy transfer (EET) in the Fenna-Matthews-Olson(FMO) complexes. In
this paper we add the quantum phase factors to the hopping terms and find that
the quantum phase factors play an important role in the EET. The quantum phase
factors allow us to consider the space structure of the pigments. It is found
that phase coherence within the complexes would allow quantum interference to
affect the dynamics of the EET. There exist some optimal phase regions where
the transfer efficiency takes its maxima, which indicates that when the
pigments are optimally spaced, the exciton can pass through the FMO with
perfect efficiency. Moreover, the optimal phase regions almost do not change
with the environments. In addition, we find that the phase factors are useful
in the EET just in the case of multiple-pathway. Therefore, we demonstrate
that, the quantum phases may bring the other two factors, the optimal space of
the pigments and multiple-pathway, together to contribute the EET in
photosynthetic complexes with perfect efficiency.Comment: 8 pages, 9 figure
Directed transport driven by the transverse wall vibration
Directed transport of overdamped Brownian particles in an asymmetrically
periodic tube is investigated in the presence of the tube wall vibration. From
the Brownian dynamics simulations we can find that the perpendicular wall
vibration can induce a net current in the longitudinal direction when the tube
is asymmetric. The direction of the current at low frequency is opposite to
that at high frequency. One can change the direction of the current by suitably
tailoring the frequency of the wall vibration.Comment: 6 pages, 7 figure
Heat conduction in deformable Frenkel-Kontorova lattices: thermal conductivity and negative differential thermal resistance
Heat conduction through the Frenkel-Kontorova (FK) lattices is numerically
investigated in the presence of a deformable substrate potential. It is found
that the deformation of the substrate potential has a strong influence on heat
conduction. The thermal conductivity as a function of the shape parameter is
nonmonotonic. The deformation can enhance thermal conductivity greatly and
there exists an optimal deformable value at which thermal conductivity takes
its maximum. Remarkably, we also find that the deformation can facilitate the
appearance of the negative differential thermal resistance (NDTR).Comment: 15 pages, 7 figure
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