10,640 research outputs found
Excited-state Forces within a First-principles Green's Function Formalism
We present a new first-principles formalism for calculating forces for
optically excited electronic states using the interacting Green's function
approach with the GW-Bethe Salpeter Equation method. This advance allows for
efficient computation of gradients of the excited-state Born-Oppenheimer
energy, allowing for the study of relaxation, molecular dynamics, and
photoluminescence of excited states. The approach is tested on photoexcited
carbon dioxide and ammonia molecules, and the calculations accurately describe
the excitation energies and photoinduced structural deformations.Comment: 2 figures and 2 table
Experimental and numerical investigations of free convection heat transfer in solar oven
The use of solar energy for baking, heating or drying represents a sustainable way of solar energy
applications with negligible negative effects. Solar oven is an alternative to conventional oven that rely
heavily on coal and wood or Electric oven that uses the power from the National grid of which the end
users have little or no control. Since the Solar oven uses no fuel and it cost nothing to run, it use are
widely promoted especially in situations where minimum fuel consumption or fire risks are considered
highly important. As useful as the Solar Oven proved, it major setback in the area of applications has
been its future sustainability. For the use of Solar Oven/Cookers to be sustained in the future, the design
and development of solar oven must rely on sound analytical tools. Therefore, this work focused on the
design and development of the solar oven. To test the performance of the Small Solar Oven a 5000cm3
beaker of water was put into the Oven and the temperature of the water was found to reach 810C after
about 3hrs under an average ambient temperature of 300C. On no load test, the oven reached a
maximum temperature of 112oC in 6hrs. In order to carry out the parametric studies and improve the
performance of the Solar Oven, Mathematical models were developed and solved by using
Characteristics-Based Split (CBS) Finite Element Method. The Model results were compared with the
Experimental results and a good agreement ware found between the two results
Classical Strongly Coupled QGP: VII. Energy Loss
We use linear response analysis and the fluctuation-dissipation theorem to
derive the energy loss of a heavy quark in the SU(2) classical Coulomb plasma
in terms of the monopole and non-static structure factor. The result is
valid for all Coulomb couplings , the ratio of the mean potential
to kinetic energy. We use the Liouville equation in the collisionless limit to
assess the SU(2) non-static structure factor. We find the energy loss to be
strongly dependent on . In the liquid phase with , the
energy loss is mostly metallic and soundless with neither a Cerenkov nor a Mach
cone. Our analytical results compare favorably with the SU(2) molecular
dynamics simulations at large momentum and for heavy quark masses.Comment: 18 pages, 15 figures. v2: added references, changed title, replaced
figures for Fig. 7, corrected typo
Coupling of Nonlocal Potentials to Electromagnetic Fields
Nonlocal Hamiltonians are used widely in first-principles quantum
calculations; the nonlocality stems from eliminating undesired degrees of
freedom, e.g. core electrons. To date, attempts to couple nonlocal systems to
external electromagnetic (EM) fields have been heuristic or limited to weak or
long wavelength fields. Using Feynman path integrals, we derive an exact,
closed-form coupling of arbitrary EM fields to nonlocal systems. Our results
justify and clarify the couplings used to date and are essential for systematic
computation of linear and especially nonlinear response.Comment: 1 figure, 1 tabl
Lessons and Prospects from the pMSSM after LHC Run I: Neutralino LSP
We study SUSY signatures at the 7, 8 and 14 TeV LHC employing the
19-parameter, R-Parity conserving p(henomenological)MSSM, in the scenario with
a neutralino LSP. Our results were obtained via a fast Monte Carlo simulation
of the ATLAS SUSY analysis suite. The flexibility of this framework allows us
to study a wide variety of SUSY phenomena simultaneously and to probe for weak
spots in existing SUSY search analyses. We determine the ranges of the
sparticle masses that are either disfavored or allowed after the searches with
the 7 and 8 TeV data sets are combined. We find that natural SUSY models with
light squarks and gluinos remain viable. We extrapolate to 14 TeV with both 300
fb and 3 ab of integrated luminosity and determine the expected
sensitivity of the jets + MET and stop searches to the pMSSM parameter space.
We find that the high-luminosity LHC will be powerful in probing SUSY with
neutralino LSPs and can provide a more definitive statement on the existence of
natural Supersymmetry.Comment: 41 pages, 27 figures. arXiv admin note: substantial text overlap with
arXiv:1307.844
Anomalous Chiral Fermi Surface
We provide a geometrical argument for the emergence of a Wess-Zumino-Witten
(WZW) term for a Fermi surface threaded by a Berry curvature. In the presence
of external fields, the gauged WZW term yields a chiral (triangle) anomaly for
the fermionic current at the edge of the Fermi surface. Fermion number is
conserved though since the Berry curvatures occur always in pairs with opposite
(monopole) charge. The anomalous vector and axial currents for a a fermionic
fluid at low temperature threaded by pairs of Berry curvatures are discussed.
The leading temperature correction to the chiral vortical effect in a slowly
rotating Fermi surface threaded by a Berry curvature maybe tied to the
gravitational anomaly.Comment: 4 pages; version to appear in PR
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