Time-dependent density functional theory for strong electromagnetic fields in crystalline solids

We apply the coupled dynamics of time-dependent density functional theory and Maxwell equations to the interaction of intense laser pulses with crystalline silicon. As a function of electromagnetic field intensity, we see several regions in the response. At the lowest intensities, the pulse is reflected and transmitted in accord with the dielectric response, and the characteristics of the energy deposition is consistent with two-photon absorption. The absorption process begins to deviate from that at laser intensities ~ 10^13 W/cm^2, where the energy deposited is of the order of 1 eV per atom. Changes in the reflectivity are seen as a function of intensity. When it passes a threshold of about 3 \times 1012 W/cm2, there is a small decrease. At higher intensities, above 2 \times 10^13 W/cm^2, the reflectivity increases strongly. This behavior can be understood qualitatively in a model treating the excited electron-hole pairs as a plasma.Comment: 27 pages; 11 figure

Effects of Collective Potentials on Pion Spectra in Relativistic Heavy Ion Collisions

The effect of collective potentials on pion spectra in ultrarelativistic heavy ion collisions is investigated. We find the effect of these potential to be very small, too small to explain the observed enhancement at low transverse momenta. (7 figures, bill be send on request)Comment: 11 page

Self-Similar Intermediate Asymptotics for a Degenerate Parabolic Filtration-Absorption Equation

The equation $$\partial_tu=u\partial^2_{xx}u-(c-1)(\partial_xu)^2$$ is known in literature as a qualitative mathematical model of some biological phenomena. Here this equation is derived as a model of the groundwater flow in a water absorbing fissurized porous rock, therefore we refer to this equation as a filtration-absorption equation. A family of self-similar solutions to this equation is constructed. Numerical investigation of the evolution of non-self-similar solutions to the Cauchy problems having compactly supported initial conditions is performed. Numerical experiments indicate that the self-similar solutions obtained represent intermediate asymptotics of a wider class of solutions when the influence of details of the initial conditions disappears but the solution is still far from the ultimate state: identical zero. An open problem caused by the nonuniqueness of the solution of the Cauchy problem is discussed.Comment: 19 pages, includes 7 figure

Energy spectrum and effective mass using a non-local 3-body interaction

We recently proposed a nonlocal form for the 3-body induced interaction that is consistent with the Fock space representation of interaction operators but leads to a fractional power dependence on the density. Here we examine the implications of the nonlocality for the excitation spectrum. In the two-component weakly interacting Fermi gas, we find that it gives an effective mass that is comparable to the one in many-body perturbation theory. Applying the interaction to nuclear matter, it predicts a large enhancement to the effective mass. Since the saturation of nuclear matter is partly due to the induced 3-body interaction, fitted functionals should treat the effective mass as a free parameter, unless the two- and three-body contributions are determined from basic theory.Comment: 7 pages, 1 figure; V2 has a table showing the 3-body energies for two phenomenological energy-density functional

Conductance of a single-atom carbon chain with graphene leads

We study the conductance of an interconnect between two graphene leads formed by a single-atom carbon chain. Its dependence on the chemical potential and the number of atoms in the chain is qualitatively different from that in the case of normal metal leads. Electron transport proceeds via narrow resonant states in the wire. The latter arise due to strong reflection at the junctions between the chain and the leads, which is caused by the small density of states in the leads at low energy. The energy dependence of the transmission coefficient near resonance is asymmetric and acquires a universal form at small energies. We find that in the case of leads with the zigzag edges the dispersion of the edge states has a significant effect on the device conductance.Comment: 9 pages, 4 figure

Nuclear composition and energy spectra in the 12 April 1969 solar particle event

Nuclear composition for several multicharged nuclei and energy spectra for hydrogen, helium, and medium nuclei measured in solar particle even

Collective oscillations of a trapped Fermi gas near the unitary limit

We calculate the oscillation frequencies of trapped Fermi condensate with particular emphasis on the equation of state of the interacting Fermi system. We confirm Stringari's finding that the frequencies are independent of the interaction in the unitary limit, and we extend the theory away from that limit, where the interaction does affect the frequencies of the compressional modes only.Comment: 4 pages, corrected a couple of trivial mistakes in table II and the related text and added reference

Surface response of spherical core-shell structured nanoparticle by optically induced elastic oscillations of soft shell against hard core

The optically induced oscillatory response of a spherical two-component, shell-core structured, nanoparticle by nodeless elastic vibrations of soft peripheral shell against hard and dynamically immobile inner core is considered. The eigenfrequencies of the even-parity, spheroidal and odd-parity torsional vibrational modes trapped in the finite-depth shell are obtained which are of practical interest for modal specification of individual resonances in spectra of resonant scattering of long wavelength electromagnetic waves by ultrafine particles.Comment: Surface Review and Letters (World Scientific) Year: 2009 Vol: 16 Issue: 1 (February 2009) Page: 5 - 1