7,427 research outputs found
Kinematic Basis of Emergent Energetics of Complex Dynamics
Stochastic kinematic description of a complex dynamics is shown to dictate an
energetic and thermodynamic structure. An energy function emerges
as the limit of the generalized, nonequilibrium free energy of a Markovian
dynamics with vanishing fluctuations. In terms of the and its
orthogonal field , a general vector field
can be decomposed into , where
.
The matrix and scalar , two additional characteristics to the
alone, represent the local geometry and density of states intrinsic to
the statistical motion in the state space at . and
are interpreted as the emergent energy and degeneracy of the motion, with an
energy balance equation ,
reflecting the geometrical . The
partition function employed in statistical mechanics and J. W. Gibbs' method of
ensemble change naturally arise; a fluctuation-dissipation theorem is
established via the two leading-order asymptotics of entropy production as
. The present theory provides a mathematical basis for P. W.
Anderson's emergent behavior in the hierarchical structure of complexity
science.Comment: 7 page
Current rectification by asymmetric molecules: An ab initio study
We study current rectification effect in an asymmetric molecule
HOOC-CH-(CH) sandwiched between two Aluminum electrodes using
an {\sl ab initio} nonequilibrium Green function method. The conductance of the
system decreases exponentially with the increasing number of CH. The
phenomenon of current rectification is observed such that a very small current
appears at negative bias and a sharp negative differential resistance at a
critical positive bias when . The rectification effect arises from the
asymmetric structure of the molecule and the molecule-electrode couplings. A
significant rectification ratio of 38 can be achieved when .Comment: to appear in J. Chem. Phy
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