25,579 research outputs found
Hydrodynamic mean field solutions of 1D exclusion processes with spatially varying hopping rates
We analyze the open boundary partially asymmetric exclusion process with
smoothly varying internal hopping rates in the infinite-size, mean field limit.
The mean field equations for particle densities are written in terms of Ricatti
equations with the steady-state current as a parameter. These equations are
solved both analytically and numerically. Upon imposing the boundary conditions
set by the injection and extraction rates, the currents are found
self-consistently. We find a number of cases where analytic solutions can be
found exactly or approximated. Results for from asymptotic analyses for
slowly varying hopping rates agree extremely well with those from extensive
Monte Carlo simulations, suggesting that mean field currents asymptotically
approach the exact currents in the hydrodynamic limit, as the hopping rates
vary slowly over the lattice. If the forward hopping rate is greater than or
less than the backward hopping rate throughout the entire chain, the three
standard steady-state phases are preserved. Our analysis reveals the
sensitivity of the current to the relative phase between the forward and
backward hopping rate functions.Comment: 12 pages, 4 figure
ATM optical contamination study - Reaction control system rocket engine space plume flow fields Interim report
Apollo telescopic experiment contamination by space vehicle exhaust product
Color centers in hexagonal boron nitride monolayers: A group theory and ab-initio analysis
We theoretically study physical properties of the most promising color center
candidates for the recently observed single-photon emissions in hexagonal boron
nitride (h-BN) monolayers. Through our group theory analysis combined with
density functional theory (DFT) calculations we provide several pieces of
evidence that the electronic properties of the color centers match the
characters of the experimentally observed emitters. We calculate the
symmetry-adapted multi-electron wavefunctions of the defects using group theory
methods and analyze the spin-orbit and spin-spin interactions in detail. We
also identify the radiative and non-radiative transition channels for each
color center. An advanced ab-initio DFT method is then used to compute energy
levels of the color centers and their zero-phonon-line (ZPL) emissions. The
computed ZPLs, the profile of excitation and emission dipole polarizations, and
the competing relaxation processes are discussed and matched with the observed
emission lines. By providing evidence for the relation between single-photon
emitters and local defects in h-BN, this work provides the first steps towards
harnessing quantum dynamics of these color centers.Comment: 11 pages, 5 figure
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