Density-functional embedding using a plane-wave basis

The constrained electron density method of embedding a Kohn-Sham system in a substrate system (first described by P. Cortona, Phys. Rev. B {\bf 44}, 8454 (1991) and T.A. Wesolowski and A. Warshel, J. Phys. Chem {\bf 97}, 8050 (1993)) is applied with a plane-wave basis and both local and non-local pseudopotentials. This method divides the electron density of the system into substrate and embedded electron densities, the sum of which is the electron density of the system of interest. Coupling between the substrate and embedded systems is achieved via approximate kinetic energy functionals. Bulk aluminium is examined as a test case for which there is a strong interaction between the substrate and embedded systems. A number of approximations to the kinetic-energy functional, both semi-local and non-local, are investigated. It is found that Kohn-Sham results can be well reproduced using a non-local kinetic energy functional, with the total energy accurate to better than 0.1 eV per atom and good agreement between the electron densities.Comment: 11 pages, 4 figure

CELL-LINED, NONWOVEN MICROFIBER SCAFFOLDS AS A BLOOD INTERFACE *

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73137/1/j.1749-6632.1977.tb41787.x.pd

Detailed Analysis of Transverse Emittance of the FLUTE Electron Bunch

The com­pact and ver­sa­tile lin­ear ac­cel­er­a­tor-based test fa­cil­ity FLUTE (Fer­n­in­frarot Linac- Und Test-Ex­per­i­ment) is op­er­ated at KIT. Its pri­mary goal is to serve as a plat­form for a va­ri­ety of ac­cel­er­a­tor R\&D stud­ies like the gen­er­a­tion of strong ul­tra-short ter­a­hertz pulses. The am­pli­tude of the gen­er­ated co­her­ent THz pulses is pro­por­tional to the square num­ber of par­ti­cles in the bunch. With the trans­verse emit­tance a mea­sure for the trans­verse par­ti­cle den­sity can be de­ter­mined. It is there­fore a vital pa­ra­me­ter in the op­ti­miza­tion for op­er­a­tion. In a sys­tem­atic study, the trans­verse emit­tance of the elec­tron beam was mea­sured in the FLUTE in­jec­tor. A de­tailed analy­sis con­sid­ers dif­fer­ent in­flu­ences such as the bunch charge and com­pares this with par­ti­cle track­ing sim­u­la­tions car­ried out with ASTRA. In this con­tri­bu­tion, the key find­ings of this analy­sis are dis­cussed

Dynamical Generation of Fermion Mass and Magnetic Field in Three-Dimensional QED with Chern-Simons Term

We study dynamical symmetry breaking in three-dimensional QED with a Chern-Simons (CS) term, considering the screening effect of $N$ flavor fermions. We find a new phase of the vacuum, in which both the fermion mass and a magnetic field are dynamically generated, when the coefficient of the CS term $\kappa$ equals $N e^2/4 \pi$. The resultant vacuum becomes the finite-density state half-filled by fermions. For $\kappa=N e^2/2 \pi$, we find the fermion remains massless and only the magnetic field is induced. For $\kappa=0$, spontaneous magnetization does not occur and should be regarded as an external field.Comment: 8 pages, no figure, to be published in Phys. Rev. Let

Electro-optical bunch length monitor for flute: Layout and simulations

A new compact linear accelerator FLUTE is currently under construction at Karlsruhe Institute of Technology (KIT) in collaboration with DESY and PSI. It aims at obtaining femtosecond electron bunches (~1fs - 300 fs) with a wide charge range (1 pC - 3 nC) and requires a precise bunch length diagnostic system. Here we present the layout of a bunch length monitor based on the electro-optic technique of spectral decoding using an Yb-doped fiber laser system (central wavelength 1030 nm) and a GaP crystal. Simulations of the electro-optic signal for different operation modes of FLUTE were performed and main challenges are discussed in this talk. This work is funded by the European Union under contract PITN-GA-2011-28919

Radiation Safety at FLUTE with Special Emphasis on Activation Issues

The accelerator FLUTE (name abbreviation derived from its German name: Ferninfrarot Linac- und TestExperiment) has been set up in cooperation with DESY and PSI [1]. The electron source and diagnostics has commenced operation. General safety issues of FLUTE are covered in this paper. The activation of the accelerator and vacuum parts were predicted previously [2]. The attention is given to the activation of aluminum and impurities in the electron absorber of the beam dump. Potential air activation in the experimental hall is also discussed

The Energy Density in the Maxwell-Chern-Simons Theory

A two-dimensional nonrelativistic fermion system coupled to both electromagnetic gauge fields and Chern-Simons gauge fields is analysed. Polarization tensors relevant in the quantum Hall effect and anyon superconductivity are obtained as simple closed integrals and are evaluated numerically for all momenta and frequencies. The correction to the energy density is evaluated in the random phase approximation (RPA), by summing an infinite series of ring diagrams. It is found that the correction has significant dependence on the particle number density. In the context of anyon superconductivity, the energy density relative to the mean field value is minimized at a hole concentration per lattice plaquette (0.05 \sim 0.06) (p_c a/\hbar)^2 where p_c and a are the momentum cutoff and lattice constant, respectively. At the minimum the correction is about -5 % \sim -25 %, depending on the ratio (2m \omega_c)/(p_c^2) where \omega_c is the frequency cutoff. In the Jain-Fradkin-Lopez picture of the fractional quantum Hall effect the RPA correction to the energy density is very large. It diverges logarithmically as the cutoff is removed, implying that corrections beyond RPA become important at large momentum and frequency.Comment: 19 pages (plain Tex), 12 figures not included, UMN-TH-1246/9