492 research outputs found
Semi-classical generalized Langevin equation for equilibrium and nonequilibrium molecular dynamics simulation
Molecular dynamics (MD) simulation based on Langevin equation has been widely
used in the study of structural, thermal properties of matters in difference
phases. Normally, the atomic dynamics are described by classical equations of
motion and the effect of the environment is taken into account through the
fluctuating and frictional forces. Generally, the nuclear quantum effects and
their coupling to other degrees of freedom are difficult to include in an
efficient way. This could be a serious limitation on its application to the
study of dynamical properties of materials made from light elements, in the
presence of external driving electrical or thermal fields. One example of such
system is single molecular dynamics on metal surface, an important system that
has received intense study in surface science. In this review, we summarize
recent effort in extending the Langevin MD to include nuclear quantum effect
and their coupling to flowing electrical current. We discuss its applications
in the study of adsorbate dynamics on metal surface, current-induced dynamics
in molecular junctions, and quantum thermal transport between different
reservoirs.Comment: 23 pages, 16 figur
Efficient routing on complex networks
In this letter, we propose a new routing strategy to improve the
transportation efficiency on complex networks. Instead of using the routing
strategy for shortest path, we give a generalized routing algorithm to find the
so-called {\it efficient path}, which considers the possible congestion in the
nodes along actual paths. Since the nodes with largest degree are very
susceptible to traffic congestion, an effective way to improve traffic and
control congestion, as our new strategy, can be as redistributing traffic load
in central nodes to other non-central nodes. Simulation results indicate that
the network capability in processing traffic is improved more than 10 times by
optimizing the efficient path, which is in good agreement with the analysis.Comment: 4 pages, 4 figure
Investigating decay process within QCD sum rule approach
In this paper, the semileptonic decays with
are investigated by using the light-cone sum rule approach.
Firstly, the neutral meson mixing scheme between , ,
and pseudoscalar gluonium is discussed in a unified way, which leads to the
direct connection between two different channels for and by the
mixing angle. Then we calculated the transition form factors
(TFFs) within QCD light-cone sum rule approach up to next-to-leading order
correction. At the large recoil point, we have
and
. Furthermore, the TFFs are
extrapolated to the whole physical -region by using the simplified
-series expansion. The behaviors of TFFs and related three angular
coefficient functions , and
are given. The differential decay widths for with respect to and are
displayed, and also lead to the branching fractions and . These results show well
agreement with the recent BESIII measurements and theoretical predictions. Then
the differential distributions and integrated predictions for three angular
observables, {\it i.e.} forward-backward asymmetries, -differential flat
terms and lepton polarization asymmetry are given separately. Lastly, we
estimate the ratio for different decay channels .Comment: 10 pages, 5 figure
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