A hybrid density functional study on the electron and hole trap states in anatase titanium dioxide.
Yamamoto, Takenori; Ohno, Takahisa
2012-01-14
We present a theoretical study on electron and hole trap states in the bulk and (001) surface of anatase titanium dioxide using screened hybrid density functional calculations. In both the bulk and surface, calculations suggest that the neutral and ionized oxygen vacancies are possible electron traps. The doubly ionized oxygen vacancy is the most stable in the bulk, and is a candidate for a shallow donor in colorless anatase crystals. The hole trap states are localized at oxygen anions in both the bulk and surface. The self-trapped electron centered at a titanium cation cannot be produced in the bulk, but can be formed at the surface. The electron trap level at the surface oxygen vacancy is consistent with observations by photoelectron spectroscopy. The optical absorptions and luminescence in UV-irradiated anatase nanoparticles are found to come from the surface self-trapped hole and the surface oxygen vacancy.
Density matrix of black hole radiation
Alberte, Lasma; Khmelnitsky, Andrei; Medved, A J M
2015-01-01
Hawking's model of black hole evaporation is not unitary and leads to a mixed density matrix for the emitted radiation, while the Page model describes a unitary evaporation process in which the density matrix evolves from an almost thermal state to a pure state. We compare a recently proposed model of semiclassical black hole evaporation to the two established models. In particular, we study the density matrix of the outgoing radiation and determine how the magnitude of the off-diagonal corrections differs for the three frameworks. For Hawking's model, we find power-law corrections to the two-point functions that induce exponentially suppressed corrections to the off-diagonal elements of the full density matrix. This verifies that the Hawking result is correct to all orders in perturbation theory and also allows one to express the full density matrix in terms of the single-particle density matrix. We then consider the semiclassical theory for which the corrections, being non-perturbative from an effective fie...
Quantum state of the black hole interior
Brustein, Ram
2015-01-01
If a black hole (BH) is initially in an approximately pure state and it evaporates by a unitary process, then the emitted radiation will be in a highly quantum state. As the purifier of this radiation, the state of the BH interior must also be in some highly quantum state. So that, within the interior region, the mean-field approximation cannot be valid and the state of the BH cannot be described by some semiclassical metric. On this basis, we model the state of the BH interior as a collection of a large number of excitations that are packed into closely spaced but single-occupancy energy levels; a sort-of "Fermi sea" of all light-enough particles. This highly quantum state is surrounded by a semiclassical region that lies close to the horizon and has a non-vanishing energy density. It is shown that such a state looks like a BH from the outside and decays via gravitational pair production in the near-horizon region at a rate that agrees with the Hawking rate. We also consider the fate of a classical object th...
Quantum state of the black hole interior
Brustein, Ram; Medved, A. J. M.
2015-08-01
If a black hole (BH) is initially in an approximately pure state and it evaporates by a unitary process, then the emitted radiation will be in a highly quantum state. As the purifier of this radiation, the state of the BH interior must also be in some highly quantum state. So that, within the interior region, the mean-field approximation cannot be valid and the state of the BH cannot be described by some semiclassical metric. On this basis, we model the state of the BH interior as a collection of a large number of excitations that are packed into closely spaced but single-occupancy energy levels; a sort-of "Fermi sea" of all light-enough particles. This highly quantum state is surrounded by a semiclassical region that lies close to the horizon and has a non-vanishing energy density. It is shown that such a state looks like a BH from the outside and decays via gravitational pair production in the near-horizon region at a rate that agrees with the Hawking rate. We also consider the fate of a classical object that has passed through to the BH interior and show that, once it has crossed over the near-horizon threshold, the object meets its demise extremely fast. This result cannot be attributed to a "firewall", as the trauma to the in-falling object only begins after it has passed through the near-horizon region and enters a region where semiclassical spacetime ends but the energy density is still parametrically smaller than Planckian.
Quantum state of the black hole interior
Energy Technology Data Exchange (ETDEWEB)
Brustein, Ram [Department of Physics, Ben-Gurion University,Beer-Sheva 84105 (Israel); Medved, A.J.M. [Department of Physics & Electronics, Rhodes University,Grahamstown 6140 (South Africa); National Institute for Theoretical Physics (NITheP),Western Cape 7602 (South Africa)
2015-08-17
If a black hole (BH) is initially in an approximately pure state and it evaporates by a unitary process, then the emitted radiation will be in a highly quantum state. As the purifier of this radiation, the state of the BH interior must also be in some highly quantum state. So that, within the interior region, the mean-field approximation cannot be valid and the state of the BH cannot be described by some semiclassical metric. On this basis, we model the state of the BH interior as a collection of a large number of excitations that are packed into closely spaced but single-occupancy energy levels; a sort-of “Fermi sea” of all light-enough particles. This highly quantum state is surrounded by a semiclassical region that lies close to the horizon and has a non-vanishing energy density. It is shown that such a state looks like a BH from the outside and decays via gravitational pair production in the near-horizon region at a rate that agrees with the Hawking rate. We also consider the fate of a classical object that has passed through to the BH interior and show that, once it has crossed over the near-horizon threshold, the object meets its demise extremely fast. This result cannot be attributed to a “firewall”, as the trauma to the in-falling object only begins after it has passed through the near-horizon region and enters a region where semiclassical spacetime ends but the energy density is still parametrically smaller than Planckian.
Energy Technology Data Exchange (ETDEWEB)
Kremer, S. [Institut fuer Theorie der Kondensierten Materie, Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe (Germany); Laboratoire CRISMAT, UMR CNRS-ENSICAEN (ISMRA) 6508, Caen (France); Fresard, R. [Laboratoire CRISMAT, UMR CNRS-ENSICAEN (ISMRA) 6508, Caen (France)
2012-01-15
Through the motivation of the recent discovery of dispersionless regions in the band structure of the delafossites, a model density of states of free fermions including a d anomaly is studied. The resulting temperature dependence of the chemical potential is obtained both exactly and by different approximation schemes which are then discussed thoroughly. This includes the introduction of an approximation of the polylogarithm difference which is capable of accessing a parameter range neither covered by Sommerfeld expansion nor by Boltzmann approximation. It is found that the Fermi temperature and several other temperature scales may be very low, giving rise to experimentally observable behaviours differing from the one described by Fermi liquid theory. In particular, two kinds of apparent Fermi liquid behaviour emerge at intermediate temperatures. This behaviour is related to recent transport data reported for CuCr{sub 1-x}Mg{sub x}O{sub 2} [A. Maignan et al., Solid State Commun. 149, 962 (2009)] and CuRh{sub 1-x}Mg{sub x}O{sub 2} [A. Maignan et al., Phys. Rev. B 80, 115103 (2009)] by means of the temperature independent correlation functions ratio approximation. In this way an effective density of states as well as the effective charge carrier density of these materials are determined. Furthermore, conclusions about the specific heat of the latter material are drawn which presents particular effects of the analytical anomaly. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Langfeld, Kurt
2016-01-01
Although Monte Carlo calculations using Importance Sampling have matured into the most widely employed method for determining first principle results in QCD, they spectacularly fail for theories with a sign problem or for which certain rare configurations play an important role. Non-Markovian Random walks, based upon iterative refinements of the density-of-states, overcome such overlap problems. I will review the Linear Logarithmic Relaxation (LLR) method and, in particular, focus onto ergodicity and exponential error suppression. Applications include the high-state Potts model, SU(2) and SU(3) Yang-Mills theories as well as a quantum field theory with a strong sign problem: QCD at finite densities of heavy quarks.
Bound States Of Supersymmetric Black Holes
Britto-Pacumio, R A
2002-01-01
The quantum mechanics of N slowly-moving supersymmetric black holes in five dimensions is considered. A divergent continuum of states describing arbitrarily closely bound black holes with arbitrarily small excitation energies is found. A superconformal structure appears at low energies and can be used to define a topological index counting the weighted number of supersymmetric bound states. It is shown that the index is determined from the dimensions of certain cohomology classes on the symmetric product of N copies of R4. This bound state index is computed exactly for two and three black holes. The required regulator for the infrared continuum of near-coincident black holes is chosen in accord with the enhanced superconformal symmetry.
Aydin, Alhun; Sisman, Altug
2016-03-01
By considering the quantum-mechanically minimum allowable energy interval, we exactly count number of states (NOS) and introduce discrete density of states (DOS) concept for a particle in a box for various dimensions. Expressions for bounded and unbounded continua are analytically recovered from discrete ones. Even though substantial fluctuations prevail in discrete DOS, they're almost completely flattened out after summation or integration operation. It's seen that relative errors of analytical expressions of bounded/unbounded continua rapidly decrease for high NOS values (weak confinement or high energy conditions), while the proposed analytical expressions based on Weyl's conjecture always preserve their lower error characteristic.
Dependence of polar hole density on magnetic and solar conditions
Hoegy, W. R.; Grebowsky, J. M.
1991-01-01
Electron densities from the Langmuir probes on the Atmospheric Explorer C and Dynamics Explorer 2 are used for analyzing the behavior of the high-altitude night-side F region polar hole as a function of solar and magnetic activity and of universal time (UT). The polar region of invariant latitude from 70 deg to 80 deg and MLT from 22 to 03 hours is examined. The strongest dependencies are observed in F10.7 and UT; a strong hemispherical difference due to the offset of the magnetic poles from the earth's rotation axis is observed in the UT dependence of the ionization hole. A seasonal variation in the dependence of ion density on solar flux is indicated, and an overall asymmetry in the density level between hemispheres is revealed, with the winter-hole density about a factor of 10 greater in the north than in the south.
Black holes with constant topological Euler density
Bargueño, Pedro
2016-01-01
A class of four dimensional spherically symmetric and static geometries with constant topological Euler density is studied. These geometries are shown to solve the coupled Einstein-Maxwell system when non-linear Born-Infeld-like electrodynamics is employed.
State Transitions of Black Hole Accretion Flows
Institute of Scientific and Technical Information of China (English)
卢炬甫; 潘刘彬
2001-01-01
We show that the thermal instability-triggered transition from the state of the Shakura-Sunyaev disc to the state of the advection-dominated accretion flow is possible for black hole accretion flows composed of two-temperature plasma with bremsstrahlung and synchrotron radiation and Comptonization.
Quantum States for Black Holes
Vargas Moniz, Paulo
2002-12-01
Interest in quantum black holes have been increasing1-2 in order to better understand the latest stages of gravitational collapse. Our starting point is the 4-dimensional action S4-D = ∫ {d4 x√ {-g} [{R4}/{16}} - {(∇ 4 ψ 4)2 }/{2}}, associated with a 4-dimensional spherically symmetric metric ds2 = hab (τ ,r)dxa dxb + φ 2 (dθ 2 + sin 2 θ dω 2), with det(hab) = -α2β In addition hat{psi}_4 (tau ,r,theta ,omega) is a scalar field depending on all space-time coordinates, with ψ 4 = ψ 0 (τ ,r) + ∑ limits n {Cn ψ n (τ,r) Qn (θ ,ω )}, where Qn are usual harmonics on S2 forming a complete orthonormal set ...
Dark Matter Density Spikes around Primordial Black Holes
Eroshenko, Yu N
2016-01-01
We show that density spikes begin to form from dark matter particles around primordial black holes immediately after their formation at the radiation-dominated cosmological stage. This follows from the fact that in the thermal velocity distribution of particles there are particles with low velocities that remain in finite orbits around black holes and are not involved in the cosmological expansion. The accumulation of such particles near black holes gives rise to density spikes. These spikes are considerably denser than those that are formed later by the mechanism of secondary accretion. The density spikes must be bright gamma-ray sources. Comparison of the calculated signal from particle annihilation with the Fermi-LAT data constrains the present-day cosmological density parameter for primordial black holes with masses $M_{\\rm BH}\\geq10^{-8}M_\\odot$ from above by values from $\\Omega_{\\rm BH}\\leq1$ to $\\Omega_{\\rm BH}\\leq10^{-8}$, depending on $M_{\\rm BH}$. These constraints are several orders of magnitude mo...
Joint density of states in low dimensional semiconductors
Cabrera, C. I.; Contreras-Solorio, D. A.; Hernández, L.
2016-02-01
We present a different approach to evaluate density of states for quasi-bidimensional systems, which bonds density of states in the confinement direction with in-plane 2D density of states. Applying the convolution operation, we propose an accurately mathematical expression that combines directly the valence band and conduction band density of states functions to generate a joint density of states for direct transitions. When considering low dimensional semiconductors, another expression is found which shows that the density of states for electrons (holes) can be calculated by convolution operations between the confinement direction and in-plane electron (hole) density of states. Using both expressions, we have calculated the quantum well and superlattice absorption coefficient, resulting in positive alignment with experimental data. A more complete description of physical absorption is achieved with this new approach.
Hologram of a pure state black hole
Roy, Shubho R.; Sarkar, Debajyoti
2015-12-01
In this paper, we extend the Hamilton-Kabat-Lifschytz-Lowe (HKLL) holographic smearing function method to reconstruct (quasi)local anti-de Sitter bulk scalar observables in the background of a large anti-de Sitter black hole formed by null shell collapse (a "pure state" black hole), from the dual conformal field theory which is undergoing a sudden quench. In particular, we probe the near horizon and subhorizon bulk locality. First, we construct local bulk operators from the conformal field theory in the leading semiclassical limit, N →∞ . Then, we look at effects due to the finiteness of N , where we propose a suitable coarse-graining prescription involving early and late time cutoffs to define semiclassical bulk observables which are approximately local, their departure from locality being nonperturbatively small in N . Our results have important implications on the black hole information problem.
Hologram of a pure state black hole
Roy, Shubho R
2015-01-01
In this paper we extend the HKLL holographic smearing function method to reconstruct (quasi)local AdS bulk scalar observables in the background of a large AdS black hole formed by null shell collapse (a "pure state" black hole), from the dual CFT which is undergoing a sudden quench. In particular, we probe the near horizon and sub-horizon bulk locality. First we construct local bulk operators from the CFT in the leading semiclassical limit, $N\\rightarrow\\infty$. Then we look at effects due to the finiteness of $N$, where we propose a suitable coarse-graining prescription involving early and late time cut-offs to define semiclassical bulk observables which are approximately local; their departure from locality being non-perturbatively small in $N$. Our results have important implications on the black hole information problem.
Cassini states for black-hole binaries
Correia, Alexandre C M
2016-01-01
Cassini states correspond to equilibria of the spin axis of a celestial body when its orbit is perturbed. They were initially described for planetary satellites, but the spin axes of black-hole binaries also present this kind of equilibria. In previous works, Cassini states were reported as spin-orbit resonances, but actually the spin of black-hole binaries is in circulation and there is no resonant motion. Here we provide a general description of the spin dynamics of black-hole binary systems based on a Hamiltonian formalism. In absence of dissipation the problem is integrable and it is easy to identify all possible trajectories for the spin for a given value of the total angular momentum. As the system collapses due to radiation reaction, the Cassini states are shifted to different positions, which modifies the dynamics around them. This is why the final spin distribution may differ from the initial one. Our method provides a simple way of predicting the distribution of the spin of black-hole binaries at th...
Oil Shale Core Hole and Rotary Hole Locations in the State of Colorado
U.S. Geological Survey, Department of the Interior — This file contains points that describe locations of oil shale core holes and rotary holes in the state of Colorado and is available as an ESRI shapefile, Google...
Black Holes and Galactic Density Cusps III From Black Hole to Bulge
Henriksen, Richard N; Macmillan, Joseph D
2011-01-01
Aims. In this paper we continue our study of density cusps that may contain central black holes. Methods. We recall our attempts to use distribution functions with a memory of self-similar relaxation, but mostly they apply only in restricted regions of the global system. We are forced to consider related distribution functions that are steady but not self-similar. Results. One remarkably simple distribution function that has a filled loss cone describes a bulge that transits from a near black hole domain to an outer 'zero flux' regime where$\\rho\\propto r^{-7/4}$. The transition passes from an initial inverse square profile through a region having a 1/r density profile. The structure is likely to be developed at an early stage in the growth of a galaxy. A central black hole is shown to grow exponentially in this background with an e-folding time of a few million years. Conclusions. We derive our results from first principles, using only the angular momentum integral in spherical symmetry. The initial relaxatio...
Institute of Scientific and Technical Information of China (English)
G K Parks; E Lee; N Lin; J B Cao; S Y Fu; J K Shi
2011-01-01
Larmor size transient structures with density depletions as large as 99% of ambient solar wind density levels occur commonly upstream of Earth＇s collisionless bow shock. These ＂density holes＂ have a mean duration of 17.9±10.4s but holes as short as 4 s have been observed. The average fractional density depletion （Sn/n） inside the holes is 0.68±0.14. The density of the upstream edge moving in the sunward direction can be enhanced by five or more times the solar wind density. Particle distributions show the steepened edge can behave like a shock, and measured local field geometries and Mach number support this view. Similarly shaped magnetic holes accompany the density holes indicating strong coupling between fields and particles. Current densities as large as 150 nA·m^-2 are observed at the leading compressed edge. The waves are elliptically polarized and rotating in the sense of ions （left hand） in the plasma frame. The waves appear to grow and steepen as the density holes convect with the solar wind toward the Earth. The transient nature of density holes suggests that the temporal features could represent the different stages of nonlinear evolutionary processes that produce a shock-like structure. The density holes are only observed with upstream particles, suggesting that back-streaming particles interacting with the solar wind are important. The significance of these observations is still being investigated.
Coexistence curves and molecule number densities of AdS black holes in the reduced parameter space
Mo, Jie-Xiong
2016-01-01
In this paper, we investigate the coexistence curves and molecule number densities of $f(R)$ AdS black holes and Gauss-Bonnet AdS black holes. Specifically, we work with the reduced parameter space and derive the analytic expressions of the universal coexistence curves that are independent of theory parameters. Moreover, we obtain the explicit expressions of the physical quantity describing the difference of the number densities of black hole molecules between the small and large black hole. It is found that both the coexistence curve and the difference of the molecule number densities of $f(R)$ AdS black holes coincide with those of RN-AdS black holes. It may be attributed to the same equation of state they share in the reduced parameter space. The difference of the molecule number densities between the small and large Gauss-Bonnet AdS black hole exhibits different behavior. This may be attributed to the fact that the charge of RN-AdS black hole is non-trivial. Our research will not only deepen the understan...
Density of basalt core from Hilo drill hole, Hawaii
Moore, James G.
2001-12-01
Density measurements of 1600 samples of core from 889 to 3097 m depth below sea level in the Hawaii Scientific Drilling Program hole near Hilo, Hawaii show marked differences between the basaltic rock types and help define stratigraphy in the hole. Water-saturated densities of subaerial lava flows (occurring above 1079 m depth) have the broadest range because of the large density variation within a single lava flow. Water-saturated densities commonly range from 2.0 to 3.0 with an average of 2.55±0.24 g/cc. Dikes and sills range from 2.8 to 3.1 g/cc). Densities of hyaloclastite commonly range from 2.3 to 2.7, with an overall average of about 2.5 g/cc. The low-density of most hyaloclastite is due primarily to palagonitization of abundant glass and presence of secondary minerals in the interstices between fragments. Four principal zones of pillow lava, separated by hyaloclastite, occur in the drill core. The shallowest (1983-2136 m) is paradoxically the densest, averaging 3.01±0.10 g/cc. The second (2234-2470 m) is decidedly the lightest, averaging 2.67±0.13 g/cc. The third (2640-2790 m) and fourth (2918-bottom at 3097 m) are high, averaging 2.89±0.17 and 2.97±0.08 g/cc, respectively. The first pillow zone includes degassed pillows i.e. lava erupted on land that flowed into the sea. These pillows are poor in vesicles, because the subaerial, one-atmosphere vesicles were compressed when the flow descended to deeper water and higher pressure. The second (low-density, non-degassed) pillow zone is the most vesicle-rich, apparently because it was erupted subaqueously at a shallow depth. The higher densities of the third and fourth zones result from a low vesicularity of only a few percent and an olivine content averaging more than 5% for the third zone and about 10% for the fourth zone. The uppermost hyaloclastite extending about 400 m below the bottom of the subaerial basalt is poorly cemented and absorbs up to 6 wt% of water when immersed. Progressing downward the
Semilocal exchange hole with an application to range-separation density functional
Tao, Jianmin; Scuseria, Gustavo E
2016-01-01
Exchange-correlation hole is a central concept in density functional theory. It not only provides justification for an exchange-correlation energy functional, but also serves as a local ingredient in nonlocal range-separation density functional. However, due to the nonlocal nature, modelig the conventional exact exchange hole presents a great challenge to density functional theory. In this work, we propose a semilocal exchange hole underlying the Tao-Perdew-Staroverov-Scuseria (TPSS) meta-GGA functional. The present model is distinct from previous models at small separation between an electron and the hole around the electron. It is also different in the way it interpolates between the rapidly varying iso-orbital density and the slowly varying density, which is determined by the wave vector analysis based on the exactly solvable infinite barrier model for jellium surface. Our numerical tests show that the exchange hole generated from this model mimics the conventional exact exchange hole quite well for atoms....
Living in a Low Density Black Hole, Non-Expanding Universe -- Perhaps a Reflecting Universe
McBryan, Bernard
2013-01-01
What is the average density of a black hole, assuming its spin can prevent it from collapsing into a singularity? For stellar black holes, the average density is incredibly dense and has over a trillion G force and tidal force that will rip almost anything apart at the black hole boundary. Surprisingly, the average density decreases dramatically for massive black holes. A black hole of 387 million solar masses would have the average density of water and would be comparable to a giant water balloon extending from the sun almost to Jupiter. A black hole of 11 billion solar masses would have the average density of air and would be analogous to a giant air filled party balloon extending 2.5 times farther out than Pluto. The average mass density in space itself, however small, eventually can become a low density black hole. If the average density of the universe matches the critical density of just 5.67 hydrogen atoms per cubic meter, it would form a Schwarzschild low density black hole of approximately 13.8 billi...
Inflation from the bang of a white hole induced from a 6D vacuum state
Energy Technology Data Exchange (ETDEWEB)
Madriz Aguilar, Jose Edgar [Departamento de Fisica, Universidade Federal da Paraiba C. Postal 5008, Joao Pessoa, PB 58059-970 (Brazil)]. E-mail: jemadriz@fisica.ufpb.br; Bellini, Mauricio [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) and Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350 (7600) Mar del Plata (Argentina)]. E-mail: mbellini@mdp.edu.ar
2007-04-26
Using ideas of STM theory, but starting from a 6D vacuum state, we propose an inflationary model where the universe emerges from the blast of a white hole. Under this approach, the expansion is affected by a geometrical deformation induced by the gravitational attraction of the hole, which should be responsible for the k{sub R}-non invariant spectrum of galaxies (and likewise of the matter density) today observed.
Energy Technology Data Exchange (ETDEWEB)
Chernov, S. V., E-mail: chernov@lpi.ru [Russian Academy of Sciences, Astrospace Center, Lebedev Physical Institute (Russian Federation)
2015-06-15
We consider the magnetohydrodynamic theory of spherically symmetric accretion of a perfect fluid onto a Schwarzschild black hole with an ultrahard equation of state, p = μ ∼ ρ{sup 2}, where p is the pressure, μ is the total energy density, and ρ is the fluid density. An approximate analytical solution is written out. We show that one critical sonic surface that coincides with the black hole event horizon is formed instead of two critical surfaces (fast and slow magnetosonic surfaces) for a degenerate ultrahard equation of state of matter.
Spatially separated charge densities of electrons and holes in organic-inorganic halide perovskites
Energy Technology Data Exchange (ETDEWEB)
Li, Dan; Liang, Chunjun, E-mail: chjliang@bjtu.edu.cn, E-mail: zhqhe@bjtu.edu.cn; Zhang, Huimin; You, Fangtian; He, Zhiqun, E-mail: chjliang@bjtu.edu.cn, E-mail: zhqhe@bjtu.edu.cn [Key Laboratory of Luminescence and Optical Information, Ministry of Education, School of Science, Beijing Jiaotong University, Beijing 100044 (China); Zhang, Chunxiu [Information Recording Materials Lab, Beijing Institute of Graphic Communication, Beijing 102600 (China)
2015-02-21
Solution-processable methylammonium lead trihalide perovskites exhibit remarkable high-absorption and low-loss properties for solar energy conversion. Calculation from density functional theory indicates the presence of non-equivalent halogen atoms in the unit cell because of the specific orientation of the organic cation. Considering the 〈100〉 orientation as an example, I{sub 1}, one of the halogen atoms, differs from the other iodine atoms (I{sub 2} and I{sub 3}) in terms of its interaction with the organic cation. The valance-band-maximum (VBM) and conduction-band-minimum (CBM) states are derived mainly from 5p orbital of I{sub 1} atom and 6p orbital of Pb atom, respectively. The spatially separated charge densities of the electrons and holes justify the low recombination rate of the pure iodide perovskite. Chlorine substitution further strengthens the unique position of the I{sub 1} atom, leading to more localized charge density around the I{sub 1} atom and less charge density around the other atoms at the VBM state. The less overlap of charge densities between the VBM and CBM states explains the relatively lower carrier recombination rate of the iodine-chlorine mixed perovskite. Chlorine substitution significantly reduces the effective mass at a direction perpendicular to the Pb-Cl bond and organic axis, enhancing the carrier transport property of the mixed perovskite in this direction.
Spatially separated charge densities of electrons and holes in organic-inorganic halide perovskites
Li, Dan; Liang, Chunjun; Zhang, Huimin; Zhang, Chunxiu; You, Fangtian; He, Zhiqun
2015-02-01
Solution-processable methylammonium lead trihalide perovskites exhibit remarkable high-absorption and low-loss properties for solar energy conversion. Calculation from density functional theory indicates the presence of non-equivalent halogen atoms in the unit cell because of the specific orientation of the organic cation. Considering the orientation as an example, I1, one of the halogen atoms, differs from the other iodine atoms (I2 and I3) in terms of its interaction with the organic cation. The valance-band-maximum (VBM) and conduction-band-minimum (CBM) states are derived mainly from 5p orbital of I1 atom and 6p orbital of Pb atom, respectively. The spatially separated charge densities of the electrons and holes justify the low recombination rate of the pure iodide perovskite. Chlorine substitution further strengthens the unique position of the I1 atom, leading to more localized charge density around the I1 atom and less charge density around the other atoms at the VBM state. The less overlap of charge densities between the VBM and CBM states explains the relatively lower carrier recombination rate of the iodine-chlorine mixed perovskite. Chlorine substitution significantly reduces the effective mass at a direction perpendicular to the Pb-Cl bond and organic axis, enhancing the carrier transport property of the mixed perovskite in this direction.
Density matrix of radiation of a black hole with a fluctuating horizon
Iofa, Mikhail Z.
2016-09-01
The density matrix of Hawking radiation is calculated in the model of a black hole with a fluctuating horizon. Quantum fluctuations smear the classical horizon of a black hole and modify the density matrix of radiation producing the off-diagonal elements. The off-diagonal elements may store information on correlations between the radiation and the black hole. The smeared density matrix was constructed by convolution of the density matrix calculated with the instantaneous horizon with the Gaussian distribution over the instantaneous horizons. The distribution has the extremum at the classical radius of the black hole and the width of order of the Planck length. Calculations were performed in the model of a black hole formed by the thin collapsing shell which follows a trajectory that is a solution of the matching equations connecting the interior and exterior geometries.
Photonic Bell states creation around rotating black holes
Racorean, Ovidiu
2016-01-01
We argue that spinning black holes are capable to implement complex quantum information processes encoded in X-ray photons emitted by the accretion disk. Recently, numerical simulations showed that X-ray photons emitted by accretion disk acquire rotation of polarization angle and orbital angular momentum due to strong gravitational field in the vicinity of the rotating black holes. Based on these two degrees of freedom we construct a bipartite two-level quantum system of the photons emitted by the accretion disk. To characterize the quantum states of this system we consider linear entropy for the reduced density matrix of polarization with the intention to exploit its direct relation with the photons degree of polarization. Since the X-ray radiation has a minimum degree of polarization located at the transition region of the accretion disk, the linear entropy is higher for the photons emitted on this region inferring a higher degree of entanglement for the composite system. We emphasize that for an extreme ro...
State-space Manifold and Rotating Black Holes
Bellucci, Stefano
2010-01-01
We study a class of fluctuating higher dimensional black hole configurations obtained in string theory/ $M$-theory compactifications. We explore the intrinsic Riemannian geometric nature of Gaussian fluctuations arising from the Hessian of the coarse graining entropy, defined over an ensemble of brane microstates. It has been shown that the state-space geometry spanned by the set of invariant parameters is non-degenerate, regular and has a negative scalar curvature for the rotating Myers-Perry black holes, Kaluza-Klein black holes, supersymmetric $AdS_5$ black holes, $D_1$-$D_5$ configurations and the associated BMPV black holes. Interestingly, these solutions demonstrate that the principal components of the state-space metric tensor admit a positive definite form, while the off diagonal components do not. Furthermore, the ratio of diagonal components weakens relatively faster than the off diagonal components, and thus they swiftly come into an equilibrium statistical configuration. Novel aspects of the scali...
On the number density of `direct collapse' black hole seeds
Habouzit, Mélanie; Volonteri, Marta; Latif, Muhammad; Dubois, Yohan; Peirani, Sébastien
2016-11-01
Supermassive black holes (BHs) reside in the centre of most local galaxies, but they also power active galactic nuclei and quasars, detected up to z = 7. These quasars put constraints on early BH growth and the mass of BH seeds. The scenario of `direct collapse' is appealing as it leads to the formation of large mass BH seeds, 104-106 M⊙, which eases explaining how quasars at z = 6-7 are powered by BHs with masses >109 M⊙. Direct collapse, however, appears to be rare, as the conditions required by the scenario are that gas is metal-free, the presence of a strong photodissociating Lyman-Werner flux, and large inflows of gas at the centre of the halo, sustained for 10-100 Myr. We performed several cosmological hydrodynamical simulations that cover a large range of box sizes and resolutions, thus allowing us to understand the impact of several physical processes on the distribution of direct collapse BHs. We identify haloes where direct collapse can happen, and derive the number density of BHs. We also investigate the discrepancies between hydrodynamical simulations, direct or post-processed, and semi-analytical studies. Under optimistic assumptions, we find that for direct collapse to account for BHs in normal galaxies, the critical Lyman-Werner flux required for direct collapse must be about two orders of magnitude lower than predicted by 3D simulations that include detailed chemical models. However, when supernova feedback is relatively weak, enough direct collapse BHs to explain z = 6-7 quasars can be obtained for Lyman-Werner fluxes about one order of magnitude lower than found in 3D simulations.
Performance of Frozen Density Embedding for Modeling Hole Transfer Reactions
Ramos, Pablo; Pavanello, Michele
2015-01-01
We have carried out a thorough benchmark of the FDE-ET method for calculating hole transfer couplings. We have considered 10 exchange-correlation functionals, 3 non-additive kinetic energy functionals and 3 basis sets. Overall, we conclude that with a 7% mean relative unsigned error, the PBE functional coupled with the PW91k non-additive Kinetic energy functional and a TZP basis set constitutes the most stable, and accurate level of theory for hole-transfer coupling calculations. The FDE-ET method is found to be an excellent tool for computing diabatic couplings for hole transfer reactions.
Near-horizon states of black holes and Calogero models
Indian Academy of Sciences (India)
B Basu-Mallick; Pijush K Ghosh; Kumar S Gupta
2004-03-01
We find self-adjoint extensions of the rational Calogero model in the presence of the harmonic interaction. The corresponding eigenfunctions may describe the near-horizon quantum states of certain types of black holes.
Lackey, Benjamin D; Shibata, Masaru; Brady, Patrick R; Friedman, John L
2011-01-01
The late inspiral, merger, and ringdown of a black hole-neutron star (BHNS) system can provide information about the neutron-star equation of state (EOS). Candidate EOSs can be approximated by a parametrized piecewise-polytropic EOS above nuclear density, matched to a fixed low-density EOS; and we report results from a large set of BHNS inspiral simulations that systematically vary two parameters. To within the accuracy of the simulations, we find that, apart from the neutron-star mass, a single physical parameter Lambda, describing its deformability, can be extracted from the late inspiral, merger, and ringdown waveform. This parameter is related to the radius, mass, and l=2 Love number, k_2, of the neutron star by Lambda = 2k_2 R^5/3M_{NS}^5, and it is the same parameter that determines the departure from point-particle dynamics during the early inspiral. Observations of gravitational waves from BHNS inspiral thus restrict the EOS to a surface of constant Lambda in the parameter space, thickened by the meas...
Photoemission spectra of charge density wave states in cuprates
Tu, Wei-Lin; Chen, Peng-Jen; Lee, Ting-Kuo
Angle-resolved photoemission spectroscopy(ARPES) experiments have reported many exotic properties of cuprates, such as Fermi arc at normal state, two gaps at superconducting state and particle-hole asymmetry at the antinodal direction. On the other hand, a number of inhomogeneous states or so-called charge density waves(CDW) states have also been discovered in cuprates by many experimental groups. The relation between these CDW states and ARPES spectra is unclear. With the help of Gutzwiller projected mean-field theory, we can reproduce the quasiparticle spectra in momentum space. The spectra show strong correspondence to the experimental data with afore-mentioned exotic features in it.
Charge carrier density dependence of the hole mobility in poly(p-phenylene vinylene)
Tanase, C; Blom, PWM; De Leeuw, DM; de Meijer, EJ
2004-01-01
The hole transport in various poly(p-phenylene vinylene) (PPV) derivatives has been investigated in field-effect transistors (FETs) and light-emitting diodes (LEDs) as a function of temperature and applied bias. The discrepancy between the experimental hole mobilities extracted from FETs and LEDs based on a single disordered polymeric semiconductor originates from the strong dependence of the hole mobility on the charge carrier density. The microscopic charge transport parameters are directly...
Density of states in La2CuO4+y
Gold, A.; Ghazali, A.
1991-06-01
We describe the excess holes in the CuO2 sheets of La2CuO4+y as a two-dimensional hole gas in a quantum well in the presence of negatively charged impurities. We calculate the density of states with a multiple-scattering approach. We discuss the broadening of the impurity band with increasing y, which corresponds to an increasing hole concentration. The spectral density, which describes for vanishing hole concentration the Fourier transform of the squared wave function, is evaluated. We compare our results with recent measurements of La2CuO4+y with y<0.007.
The generalization of charged AdS black hole specific volume and number density
Wang, Zi-Liang; He, Miao; Fang, Chao; Sun, Dao-Quan; Deng, Jian-Bo
2017-04-01
In this paper, by proposing a generalized specific volume, we restudy the P- V criticality of charged AdS black holes in the extended phase space. The results show that most of the previous conclusions can be generalized without change, but the ratio {\\tilde{ρ }}_c should be 3 {\\tilde{α }}/16 in general case. Further research on the thermodynamical phase transition of black hole leads us to a natural interpretation of our assumption, and more black hole properties can be generalized. Finally, we study the number density for charged AdS black hole in higher dimensions, the results show the necessity of our assumption.
Black hole state degeneracy in Loop Quantum Gravity
Agullo, Ivan; Fernandez-Borja, Enrique
2008-01-01
The combinatorial problem of counting the black hole quantum states within the Isolated Horizon framework in Loop Quantum Gravity is analyzed. A qualitative understanding of the origin of the band structure shown by the degeneracy spectrum, which is responsible for the black hole entropy quantization, is reached. Even when motivated by simple considerations, this picture allows to obtain analytical expressions for the most relevant quantities associated to this effect.
Initial-State Graviton Radiation in Quantum Black Hole Production
AUTHOR|(CDS)2262067
2017-01-01
Monte Carlo simulation of quantum black hole production in the ATLAS experiment that allows for graviton radiation in the initial state is discussed and studied. It is concluded that, using trapped surface calculations and graviton emission, a black hole signal would be significant for Planck scales up to 4.5 TeV given a proton-proton luminosity of 37 fb$^{-1}$ in the 13 TeV LHC configuration.
Bound states of spinning black holes in five dimensions
Crichigno, P Marcos; Vandoren, Stefan
2016-01-01
We find and study supergravity BPS bound states of five-dimensional spinning black holes in asymptotically flat spacetime. These solutions follow from multi-string solutions in six-dimensional minimal supergravity and can be uplifted to F-theory or M-theory. We analyze the regularity conditions and work out the example of a bound state of two black holes in detail. The bound state is supported by fluxes through nontrivial topologies exterior to the horizons and KK momentum. Furthermore, we determine the entropy and compare with other macroscopic BPS solutions.
Relationship between hole density and charge-ordering wave vector in Sr14-xCaxCu24O41
Rusydi, A.; Berciu, M.; Abbamonte, P.; Smadici, S.; Eisaki, H.; Fujimaki, Y.; Uchida, S.; Ruebhausen, M.; Sawatzky, G. A.
2007-01-01
The distribution of holes in Sr14-xCaxCu24O41 is revisited with semiempirical reanalysis of the x-ray absorption data and exact diagonalization cluster calculations. Another interpretation of the XAS data leads to much larger ladder hole densities than previously suggested. These new hole densities
Dressed Hard States and Black Hole Soft Hair.
Mirbabayi, Mehrdad; Porrati, Massimo
2016-11-18
A recent, intriguing Letter by Hawking, Perry, and Strominger suggests that soft photons and gravitons can be regarded as black hole hair and may be relevant to the black hole information paradox. In this Letter we make use of factorization theorems for infrared divergences of the S matrix to argue that by appropriately dressing in and out hard states, the soft-quanta-dependent part of the S matrix becomes essentially trivial. The information paradox can be fully formulated in terms of dressed hard states, which do not depend on soft quanta.
Dressed Hard States and Black Hole Soft Hair
Mirbabayi, Mehrdad; Porrati, Massimo
2016-11-01
A recent, intriguing Letter by Hawking, Perry, and Strominger suggests that soft photons and gravitons can be regarded as black hole hair and may be relevant to the black hole information paradox. In this Letter we make use of factorization theorems for infrared divergences of the S matrix to argue that by appropriately dressing in and out hard states, the soft-quanta-dependent part of the S matrix becomes essentially trivial. The information paradox can be fully formulated in terms of dressed hard states, which do not depend on soft quanta.
Semilocal exchange hole with an application to range-separated density functionals
Tao, Jianmin; Bulik, Ireneusz W.; Scuseria, Gustavo E.
2017-03-01
The exchange-correlation hole is a central concept in density functional theory. It not only provides justification for an exchange-correlation energy functional but also serves as a local ingredient for nonlocal range-separated density functionals. However, due to the nonlocal nature, modeling the conventional exact exchange hole presents a great challenge to density functional theory. In this work, we propose a semilocal exchange hole underlying the Tao-Perdew-Staroverov-Scuseria (TPSS) meta-generalized gradient approximation functional. Our model is distinct from previous ones not only at small separation between an electron and the hole around the electron but also in the way it interpolates between rapidly varying and slowly varying densities. Here the interpolation is determined by the wave-vector analysis on the infinite-barrier model for a jellium surface. Numerical tests show that our exchange-hole model mimics the conventional exact one quite well for atoms. As a simple application, we apply the hole model to construct a TPSS-based range-separated functional. We find that this range-separated functional can substantially improve the band gaps and barrier heights of TPSS, without losing much accuracy for atomization energies.
Dirac dynamical resonance states around Schwarzschild black holes
Zhou, Xiang-Nan; Yang, Ke; Liu, Yu-Xiao
2013-01-01
Recently, a novel kind of scalar wigs around Schwarzschild black holes---scalar dynamical resonance states were introduced in [Phys. Rev. D 84, 083008 (2011)] and [Phys. Rev. Lett. 109, 081102 (2012)]. In this paper, we investigate the existence and evolution of Dirac dynamical resonance states. First we look for stationary resonance states of a Dirac field around a Schwarzchild black hole by using the Schrodinger-like equations reduced from the Dirac equation in Schwarzschild spacetime. Then Dirac pseudo-stationary configurations are constructed from the stationary resonance states. We use these configurations as initial data and investigate their numerical evolutions and energy decay. These dynamical solutions are the so-called "Dirac dynamical resonance states". It is found that the energy of the Dirac dynamical resonance states shows an exponential decay. The decay rate of energy is affected by the resonant frequency, the mass of Dirac field, the total angular momentum, and the spin-orbit interaction. In ...
Superfluid density in cuprates: hints on gauge compositeness of the holes
Marchetti, P A
2016-01-01
We show that several features (the three-dimensional XY universality for moderate underdoping, the almost-BCS behaviour for moderate overdoping and the critical exponent) of the superfluid density in hole-doped cuprates hint at a composite structure of the holes. This idea can be implemented in a spin-charge gauge approach to the $t - t' - J$ model and provides indeed good agreement with available experimental data.
Plasma dynamics near critical density inferred from direct measurements of laser hole boring.
Gong, Chao; Tochitsky, Sergei Ya; Fiuza, Frederico; Pigeon, Jeremy J; Joshi, Chan
2016-06-01
We have used multiframe picosecond optical interferometry to make direct measurements of the hole boring velocity, v_{HB}, of the density cavity pushed forward by a train of CO_{2} laser pulses in a near critical density helium plasma. As the pulse train intensity rises, the increasing radiation pressure of each pulse pushes the density cavity forward and the plasma electrons are strongly heated. After the peak laser intensity, the plasma pressure exerted by the heated electrons strongly impedes the hole boring process and the v_{HB} falls rapidly as the laser pulse intensity falls at the back of the laser pulse train. A heuristic theory is presented that allows the estimation of the plasma electron temperature from the measurements of the hole boring velocity. The measured values of v_{HB}, and the estimated values of the heated electron temperature as a function of laser intensity are in reasonable agreement with those obtained from two-dimensional numerical simulations.
Brittleness and Packing Density Effects on Blast-hole Cuttings Yield of Selected Rocks
Directory of Open Access Journals (Sweden)
B. Adebayo
2016-06-01
Full Text Available This paper evaluates brittleness and packing density to analysis their effects on blast-hole cutting yield for three selected rocks in Nigeria. Brittleness test (S20 was carried out in accordance with Norwegian Soil and Rock Engineering and the Brittleness Index (BI for the selected rocks were estimated. The packing density determined from the photomicrograph of the rock samples. The grain size of 45 blast-holes drill cuttings collected from three selected while drilling of these rocks were determined using standard method of America Society for Testing and Materials (ASTM D 2487. The brittleness values are 50%, 44% and 42% for micro granite, porphyritic granite and medium biotite granite respectively. The result of BI varied from 10.32 – 11.59 and they are rated as moderately brittle rocks. The values of packing density varied from 92.20 – 94.55%, 91.00 -92.96% and 92.92 – 94.96% for all the rocks. The maximum weights of blast-hole particle size retained at 75 µm are 106.00g, 103.28 g and 99.76 g for medium biotite granite, micro granite and porhyritic granite respectively. Packing density values have correlation to some extent with (S20 values hence, this influence the yield of blast-hole cuttings as drilling progresses. The minimum weight of blast-hole cuttings particle size retained at 150 µm agrees with brittleness index classification for micro granite.
On the number density of "direct collapse" black hole seeds
Habouzit, Melanie; Latif, Muhammad; Dubois, Yohan; Peirani, Sebastien
2016-01-01
Supermassive black holes (BHs) of millions solar masses and above reside in the center of most local galaxies, but they also power active galactic nuclei and quasars, detected up to z=7. This observational evidence puts strong constraints on the BH growth and the mass of the first BH seeds. The scenario of "direct collapse" is very appealing as it leads to the formation of large mass BH seeds in the range 10^4-10^6 Msun, which eases explaining how quasars at z=6-7 are powered by BHs with masses >10^9 Msun. Direct collapse, however, appears to be rare, as the conditions required by the scenario are that gas is metal-free, the presence of a strong photo-dissociating Lyman-Werner flux, and large inflows of gas at the center of the halo, sustained for 10-100 Myr. We performed several cosmological hydrodynamical simulations that cover a large range of box sizes and resolutions, thus allowing us to understand the impact of several physical processes on the distribution of direct collapse BHs. We identify halos wher...
Static black holes in equilibrium with matter: nonlinear equation of state
Zaslavskii, Oleg B
2010-01-01
We consider a spherically symmetric black hole in equilibrium with surrounding classical matter that is characterized by a nonlinear dependence of the radial pressure p_{r} on the density {\\rho}. We examine under which requirements such an equilibrium is possible. It is shown that if the radial and transverse pressures are equal (Pascal perfect fluid), equation of state should be approximately linear near the horizon. The corresponding restriction on ((dp_{r})/(d{\\rho})) is a direct generalization of the result, previously found for an exactly linear equation of state. In the anisotropic case there is no restriction on equation of state but the horizon should be simple (nondegenerate).
Heidrich-Meisner, Verena; Peleikis, Thies; Kruse, Martin; Berger, Lars; Wimmer-Schweingruber, Robert
2016-09-01
Context. The solar wind originating from coronal holes is comparatively well-understood and is characterized by lower densities and average charge states compared to the so-called slow solar wind. Except for wave perturbations, the average properties of the coronal-hole solar wind are passably constant. Aims: In this case study, we focus on observations of the Solar Wind Ion Composition Spectrometer (SWICS) on the Advanced Composition Explorer (ACE) of individual streams of coronal-hole solar wind that illustrate that although the O and C charge states are low in coronal-hole wind, the Fe charge distribution is more variable. In particular, we illustrate that the Fe charge states in coronal-hole solar wind are frequently as high as in slow solar wind. Methods: We selected individual coronal-hole solar wind streams based on their collisional age as well as their respective O and C charge states and analyzed their Fe charge-state distributions. Additionally, with a combination of simple ballistic back-mapping and the potential field source surface model, transitions between streams with high and low Fe charge states were mapped back to the photosphere. The relative frequency of high and low Fe charge-state streams is compared for the years 2004 and 2006. Results: We found several otherwise typical coronal-hole streams that include Fe charge states either as high as or lower than in slow solar wind. Eight such transitions in 2006 were mapped back to equatorial coronal holes that were either isolated or connected to the northern coronal-hole. Attempts to identify coronal structures associated with the transitions were so far inconclusive.
Big-hole drilling - the state of the art
Energy Technology Data Exchange (ETDEWEB)
Lackey, M.D.
1983-01-01
The art of big-hole drilling has been in a continual state of evolution at the Nevada Test Site since the start of underground testing in 1961. Emplacement holes for nuclear devices are still being drilled by the rotary-drilling process, but almost all the hardware and systems have undergone many changes during the intervening years. The current design of bits, cutters, and other big-hole-drilling hardware results from contributions of manufacturers and Test Site personnel. The dual-string, air-lift, reverse-circulation system was developed at the Test Site. Necessity was really the Mother of this invention, but this circulation system is worthy of consideration under almost any condition. Drill rigs for big-hole drilling are usually adaptations of large oil-well drill rigs with minor modifications required to handle the big bits and drilling assemblies. Steel remains the favorite shaft lining material, but a lot of thought is being given to concrete linings, especially precast concrete.
Area, depth and elevation of cryoconite holes in the Arctic do not influence Tardigrada densities
Directory of Open Access Journals (Sweden)
Zawierucha Krzysztof
2016-06-01
Full Text Available Water bears (Tardigrada are known as one of the most extremophile animals in the world. They inhabit environments from the deepest parts of the oceans up to the highest mountains. One of the most extreme and still poorly studied habitats which tardigrades inhabit are cryoconite holes. We analysed the relation between area, depth, elevation and tardigrades densities in cryoconite holes on four glaciers on Spitsbergen. The mean (±SD of cryoconite area was 1287.21±2400.8 cm2, while the depth was on average 10.8±11.2 cm, the elevation 172.6±109.66 m a.s.l., and tardigrade density 24.9±33.0 individuals per gram of wet material (n = 38. The densities of tardigrades on Hans Glacier reached values of up to 168 ind. cm3, 104 ind. g−1 wet weight, and 275 ind. g−1 dry weight. The densities of tardigrades of the three glaciers in Billefjorden were up to 82 ind. cm2, 326 ind. g−1 wet weight and 624 ind. g−1 dry weight. Surprisingly, although the model included area, depth and elevation as independent variables, it cannot explain Tardigrada density in cryoconite holes. We propose that due to the rapid melting of the glacier surface in the Arctic, the constant flushing of cryoconite sediments, and inter-hole water-sediment mixing, the functioning of these ecosystems is disrupted. We conclude that cryoconite holes are dynamic ecosystems for microinvertebrates in the Arctic.
Kondo effect at low electron density and high particle-hole asymmetry in 1D, 2D, and 3D
Žitko, Rok; Horvat, Alen
2016-09-01
Using the perturbative scaling equations and the numerical renormalization group, we study the characteristic energy scales in the Kondo impurity problem as a function of the exchange coupling constant J and the conduction-band electron density. We discuss the relation between the energy gain (impurity binding energy) Δ E and the Kondo temperature TK. We find that the two are proportional only for large values of J , whereas in the weak-coupling limit the energy gain is quadratic in J , while the Kondo temperature is exponentially small. The exact relation between the two quantities depends on the detailed form of the density of states of the band. In the limit of low electron density the Kondo screening is affected by the strong particle-hole asymmetry due to the presence of the band-edge van Hove singularities. We consider the cases of one- (1D), two- (2D), and three-dimensional (3D) tight-binding lattices (linear chain, square lattice, cubic lattice) with inverse-square-root, step-function, and square-root onsets of the density of states that are characteristic of the respective dimensionalities. We always find two different regimes depending on whether TK is higher or lower than μ , the chemical potential measured from the bottom of the band. For 2D and 3D, we find a sigmoidal crossover between the large-J and small-J asymptotics in Δ E and a clear separation between Δ E and TK for TKband edge. Furthermore, we find that in 1D the particle-hole asymmetry leads to a large decrease of TK compared to the standard result obtained by approximating the density of states to be constant (flat-band approximation), while in 3D the opposite is the case; this is due to the nontrivial interplay of the exchange and potential scattering renormalization in the presence of particle-hole asymmetry. The 2D square-lattice density of states behaves to a very good approximation as a band with constant density of states.
Hole doped Dirac states in silicene by biaxial tensile strain
Kaloni, Thaneshwor P.
2013-03-11
The effects of biaxial tensile strain on the structure, electronic states, and mechanical properties of silicene are studied by ab-initio calculations. Our results show that up to 5% strain the Dirac cone remains essentially at the Fermi level, while higher strain induces hole doped Dirac states because of weakened Si–Si bonds. We demonstrate that the silicene lattice is stable up to 17% strain. It is noted that the buckling first decreases with the strain (up to 10%) and then increases again, which is accompanied by a band gap variation. We also calculate the Grüneisen parameter and demonstrate a strain dependence similar to that of graphene.
Hole boring velocity measurements in near critical density plasmas by a CO2 laser pulse
Gong, Chao; Tochitsky, Sergei; Pigeon, Jeremy; Joshi, Chan
2014-10-01
Measurements of plasma dynamics during the interaction of a high-power laser pulse with an above critical density plasma is important for understanding absorption, transport and particle acceleration mechanisms. An important process that affects these mechanisms is hole boring occurring at the critical density because of the radiation pressure of the laser pulse. Yet, no systematic measurements of the hole boring velocity's (vhb) dependence on laser intensity (I) have been made. In this talk, we present experimental results of vhb in near critical density plasmas produced by CO2 laser as a function of I in the range of 1*1015 to 1.6*1016 W/cm2. A novel four frame Mach-Zehnder interferometer using a 1 ps, 532 nm probe laser pulse was developed to record the evolution of the plasma density profile and the motion of the near critical density layer. Using this diagnostic, we observed the motion of the steepened plasma profile due to the incident, time-structured CO2 laser pulse. Experimental results show the hole boring velocity increases from 0.004c to 0.007c as the laser intensity is increased from 1*1015 to 1.6*1016 W/cm2. This work is supported by DOE grant DE-FG02-92-ER40727, NSF grant PHY-0936266 at UCLA.
Thermodynamics of Coherent States and Black Hole Entropy
Bashkirov, A G
2001-01-01
Mean values of any observable variable are always calculated in a coherent state as in a mixed state because the coherent state is an eigenstate of non-Hermitian operator. Thus, we propose the concept of a coherent ensemble closely resemble the canonical ensemble. The entropy and temperature are naturally defined for the coherent ensemble. As an example, entropy and temperature are evaluated for coherent states of a harmonic oscillator and quantum field described by the Klein-Gordon-Fock equation with a source term. It is shown, in particular, that the temperature of the coherent oscillator coincides with the effective temperature of a harmonic oscillator being in contact with a heath bath (Bloch formula) when the bath temperature tends to zero. The Bekenstein-Hawking entropy and temperature of a black hole can also be interpreted as an entropy and temperature of coherent states of a physical vacuum in the vicinity of a horizon surface.
Laser-driven hole boring and gamma-ray emission in high-density plasmas
Nerush, Evgeny
2014-01-01
Ion acceleration in laser-produced dense plasmas is a key topic of many recent investigations thanks to its potential applications. Besides, at forthcoming laser intensities ($I \\gtrsim 10^{23} \\text{W}\\,\\text{cm}^{-2}$) interaction of laser pulses with plasmas can be accompanied by copious gamma-ray emission. Here we demonstrate the mutual influence of gamma-ray emission and ion acceleration during relativistic hole boring in high-density plasmas with ultra-intense laser pulses. If gamma-ray emission is abundant, laser pulse reflection and hole-boring velocity are lower and gamma-ray radiation pattern is narrower than in the case of low emission. Conservation of energy and momentum allows one to elucidate the effects of gamma-ray emission which are more pronounced at higher hole-boring velocities.
On d+id Density Wave and Superconducting Orderings in Hole-Doped Cuprates
Goswami, Partha; Gahlot, Ajay Pratap Singh; Singh, Pankaj
2013-05-01
The d+id-density wave (chiral DDW) order, at the anti-ferromagnetic wave vector Q = (π, π), is assumed to represent the pseudo-gap (PG) state of a hole-doped cuprate superconductor. The pairing interaction U(k, k‧) required for d+id ordering comprises of (Ux2-y2(k, k‧), Uxy(k, k‧)), where Ux2-y2(k, k') = U1(cos kxa-cos kya)(cos k'xa- cos k'ya) and Uxy(k, k') = U2sin(kxa)sin(kya) sin(k'xa) sin(k'ya) with U1 > U2. The d-wave superconductivity (DSC), driven by an assumed attractive interaction of the form V(k, k') = -ěrt V1ěrt(cos kxa-cos kya)(cos k'xa- cos k'ya) where V1 is a model parameter, is discussed within the mean-field framework together with the d+id ordering. The single-particle excitation spectrum in the CDDW + DSC state is characterized by the Bogoluibov quasi-particle bands — a characteristic feature of SC state. The coupled gap equations are solved self-consistently together with the equation to determine the chemical potential (μ). With the pinning of the van Hove-singularities close to μ, one is able to calculate the thermodynamic and transport properties of the under-doped cuprates in a consistent manner. The electron specific heat displays non-Fermi liquid feature in the CDDW state. The CDDW and DSC are found to represent two competing orders as the former brings about a depletion of the spectral weight (and Raman response function density) available for pairing in the anti-nodal region of momentum space. It is also shown that the depletion of the spectral weight below Tc at energies larger than the gap amplitude occurs. This is an indication of the strong-coupling superconductivity in cuprates. The calculation of the ratio of the quasi-particle thermal conductivity αxx and temperature in the superconducting phase is found to be constant in the limit of near-zero quasi-particle scattering rate.
Hadronic density of states from string theory.
Pando Zayas, Leopoldo A; Vaman, Diana
2003-09-12
We present an exact calculation of the finite temperature partition function for the hadronic states corresponding to a Penrose-Güven limit of the Maldacena-Nùñez embedding of the N=1 super Yang-Mills (SYM) into string theory. It is established that the theory exhibits a Hagedorn density of states. We propose a semiclassical string approximation to the finite temperature partition function for confining gauge theories admitting a supergravity dual, by performing an expansion around classical solutions characterized by temporal windings. This semiclassical approximation reveals a hadronic energy density of states of a Hagedorn type, with the coefficient determined by the gauge theory string tension as expected for confining theories. We argue that our proposal captures primarily information about states of pure N=1 SYM theory, given that this semiclassical approximation does not entail a projection onto states of large U(1) charge.
Engineering photonic density of states using metamaterials
DEFF Research Database (Denmark)
Jacob, Z.; Kim, J.Y.; Naik, G.V.;
2010-01-01
The photonic density of states (PDOS), like its electronic counterpart, is one of the key physical quantities governing a variety of phenomena and hence PDOS manipulation is the route to new photonic devices. The PDOS is conventionally altered by exploiting the resonance within a device such as a......The photonic density of states (PDOS), like its electronic counterpart, is one of the key physical quantities governing a variety of phenomena and hence PDOS manipulation is the route to new photonic devices. The PDOS is conventionally altered by exploiting the resonance within a device...... such as a microcavity or a bandgap structure like a photonic crystal. Here we show that nanostructured metamaterials with hyperbolic dispersion can dramatically enhance the photonic density of states paving the way for metamaterial-based PDOS engineering....
Electron-Acoustic Compressive Soliton and Electron Density Hole in Aurora
Institute of Scientific and Technical Information of China (English)
王德焴
2003-01-01
Electron-acoustic solitary waves have been studied in an electron-beam plasma system. It is found that the solution of compressive soliton only exists within a limited range of soliton velocity around the electron beam velocity. A compressive electron-acoustic soliton always accompanies with a cold electron density hole. This theoretical model is used to explain the ‘fast solitary wave' event observed by the FAST satellite in the midaltitude auroral zone.
Density of states in La sub 2 CuO sub 4+ y
Energy Technology Data Exchange (ETDEWEB)
Gold, A. (Physik Department, Technische Universitaet Muenchen, 8046 Garching, Germany (DE)); Ghazali, A. (Groupe de Physique des Solides, Universite de Paris VI VII, 75251 Paris, France (FR))
1991-06-01
We describe the excess holes in the CuO{sub 2} sheets of La{sub 2}CuO{sub 4+{ital y}} as a two-dimensional hole gas in a quantum well in the presence of negatively charged impurities. We calculate the density of states with a multiple-scattering approach. We discuss the broadening of the impurity band with increasing {ital y}, which corresponds to an increasing hole concentration. The spectral density, which describes for vanishing hole concentration the Fourier transform of the squared wave function, is evaluated. We compare our results with recent measurements of La{sub 2}CuO{sub 4+{ital y}} with {ital y}{lt}0.007.
Gamma-Ray Spectral States of Galactic Black Hole Candidates
Grove, J E; Kroeger, R A; McNaron-Brown, K; Skibo, J G; Phlips, B F
1998-01-01
OSSE has observed seven transient black hole candidates: GRO J0422+32, GX339-4, GRS 1716-249, GRS 1009-45, 4U 1543-47, GRO J1655-40, and GRS 1915+105. Two gamma-ray spectral states are evident and, based on a limited number of contemporaneous X-ray and gamma-ray observations, these states appear to be correlated with X-ray states. The former three objects show hard spectra below 100 keV (photon number indices Gamma < 2) that are exponentially cut off with folding energy ~100 keV, a spectral form that is consistent with thermal Comptonization. This "breaking gamma-ray state" is the high-energy extension of the X-ray low, hard state. In this state, the majority of the luminosity is above the X-ray band, carried by photons of energy ~100 keV. The latter four objects exhibit a "power-law gamma-ray state" with a relatively soft spectral index (Gamma ~ 2.5-3) and no evidence for a spectral break. For GRO J1655-40, the lower limit on the break energy is 690 keV. GRS 1716-249 exhibits both spectral states, with th...
Engineering photonic density of states using metamaterials
DEFF Research Database (Denmark)
Jacob, Z.; Kim, J.Y.; Naik, G.V.
2010-01-01
The photonic density of states (PDOS), like its electronic counterpart, is one of the key physical quantities governing a variety of phenomena and hence PDOS manipulation is the route to new photonic devices. The PDOS is conventionally altered by exploiting the resonance within a device such as a...... such as a microcavity or a bandgap structure like a photonic crystal. Here we show that nanostructured metamaterials with hyperbolic dispersion can dramatically enhance the photonic density of states paving the way for metamaterial-based PDOS engineering....
Influence of gas pressure state on the motion parameters of coal-gas flow in the outburst hole
Institute of Scientific and Technical Information of China (English)
SUN Dong-ling; LIANG Yun-pei; MIAO Fa-tian
2007-01-01
Carried on the one-dimensional analysis to the motion state of coal-gas flow in the outburst hole, and deduced the relational expression between the motion parameters (containing of velocity, flow rate and density etc.) of bursting coal-gas flow and gas pressure in the hole, then pointed out the critical state change of coal-gas flow under different pressure conditions which had the very tremendous influence on both stability and destructiveness of the entire coal and gas outburst system. The mathematical processing and results of one-dimensional flow under the perfect condition are simple and explicit in this paper, which has the certain practical significance.
State-Space Geometry, Statistical Fluctuations, and Black Holes in String Theory
Directory of Open Access Journals (Sweden)
Stefano Bellucci
2014-01-01
Full Text Available We study the state-space geometry of various extremal and nonextremal black holes in string theory. From the notion of the intrinsic geometry, we offer a state-space perspective to the black hole vacuum fluctuations. For a given black hole entropy, we explicate the intrinsic geometric meaning of the statistical fluctuations, local and global stability conditions, and long range statistical correlations. We provide a set of physical motivations pertaining to the extremal and nonextremal black holes, namely, the meaning of the chemical geometry and physics of correlation. We illustrate the state-space configurations for general charge extremal black holes. In sequel, we extend our analysis for various possible charge and anticharge nonextremal black holes. From the perspective of statistical fluctuation theory, we offer general remarks, future directions, and open issues towards the intrinsic geometric understanding of the vacuum fluctuations and black holes in string theory.
State-space Geometry, Statistical Fluctuations and Black Holes in String Theory
Bellucci, Stefano
2011-01-01
We study the state-space geometry of various extremal and nonextremal black holes in string theory. From the notion of the intrinsic geometry, we offer a new perspective of black hole vacuum fluctuations. For a given black hole entropy, we explicate the intrinsic state-space geometric meaning of the statistical fluctuations, local and global stability conditions and long range statistical correlations. We provide a set of physical motivations pertaining to the extremal and nonextremal black holes, \\textit{viz.}, the meaning of the chemical geometry and physics of correlation. We illustrate the state-space configurations for general charge extremal black holes. In sequel, we extend our analysis for various possible charge and anticharge nonextremal black holes. From the perspective of statistical fluctuation theory, we offer general remarks, future directions and open issues towards the intrinsic geometric understanding of the vacuum fluctuations and black holes in string theory. Keywords: Intrinsic Geometry; ...
An Estimate of Solar Wind Density and Velocity Profiles in a Coronal Hole and a Coronal Streamer
Patzold, M.; Tsurutani, B. T.; Bird, M. K.
1996-01-01
Using the total electron content data obtained by the Ulysses Solar Corona Experiment (SCE) during the first solar conjunction in summer 1991, two data sets were selected, one associated with a coronal hole and the other associated with coronal streamer crossings. In order to determine coronal streamer density profiles, the electron content of the tracking passes embedded in a coronal streamer were corrected for the contributions from coronal hole densities.
Explosion and final state of the charged black hole bomb
Sanchis-Gual, Nicolas; Montero, Pedro J; Font, José A; Herdeiro, Carlos
2015-01-01
A Reissner-Nordstr\\"om black hole (BH) is superradiantly unstable against spherical perturbations of a charged scalar field, enclosed in a cavity, with frequency lower than a critical value. We use numerical relativity techniques to follow the development of this unstable system -- dubbed charged BH bomb -- into the non-linear regime, solving the full Einstein--Maxwell--Klein-Gordon equations, in spherical symmetry. We show that: $i)$ the process stops before all the charge is extracted from the BH; $ii)$ the system settles down into a hairy BH: a charged horizon in equilibrium with a scalar field condensate, whose phase is oscillating at the (final) critical frequency. For low scalar field charge, $q$, the final state is approached smoothly and monotonically. For large $q$, however, the energy extraction overshoots and an explosive phenomenon, akin to a $bosenova$, pushes some energy back into the BH. The charge extraction, by contrast, does not reverse.
Perturbation calculation of thermodynamic density of states.
Brown, G; Schulthess, T C; Nicholson, D M; Eisenbach, M; Stocks, G M
2011-12-01
The density of states g (ε) is frequently used to calculate the temperature-dependent properties of a thermodynamic system. Here a derivation is given for calculating the warped density of states g*(ε) resulting from the addition of a perturbation. The method is validated for a classical Heisenberg model of bcc Fe and the errors in the free energy are shown to be second order in the perturbation. Taking the perturbation to be the difference between a first-principles quantum-mechanical energy and a corresponding classical energy, this method can significantly reduce the computational effort required to calculate g(ε) for quantum systems using the Wang-Landau approach.
The Virasoro Gibbs state and BTZ black holes
Garbarz, Alan
2016-01-01
We show that the Virasoro Gibbs state accurately describes the thermodynamics of BTZ black holes at large temperatures and in the strong-coupling regime $c<1$. We first give a simple heuristic argument by showing that at high temperatures and arbitrary $c$, the energies are much larger than Planck mass. Then we give a detailed analysis of the quantum fluctuations of the Gibbs state on unitary irreducible representations of Virasoro group and explicitly show that they go to zero in the high-temperature limit by means of representation theory results. This implies the state has a sensible thermodynamic limit which actually holds for any $c$. Finally, the matching with BTZ thermodynamics for $c<1$ is obtained by using the known asymptotic behaviour of the characters of the Virasoro discrete series. This result supports the idea that minimal models could describe quantum gravity at strong coupling. We make no use of the Euclidean path integral nor assume modular invariance of the partition functions, althou...
Density functional theory in the solid state.
Hasnip, Philip J; Refson, Keith; Probert, Matt I J; Yates, Jonathan R; Clark, Stewart J; Pickard, Chris J
2014-03-13
Density functional theory (DFT) has been used in many fields of the physical sciences, but none so successfully as in the solid state. From its origins in condensed matter physics, it has expanded into materials science, high-pressure physics and mineralogy, solid-state chemistry and more, powering entire computational subdisciplines. Modern DFT simulation codes can calculate a vast range of structural, chemical, optical, spectroscopic, elastic, vibrational and thermodynamic phenomena. The ability to predict structure-property relationships has revolutionized experimental fields, such as vibrational and solid-state NMR spectroscopy, where it is the primary method to analyse and interpret experimental spectra. In semiconductor physics, great progress has been made in the electronic structure of bulk and defect states despite the severe challenges presented by the description of excited states. Studies are no longer restricted to known crystallographic structures. DFT is increasingly used as an exploratory tool for materials discovery and computational experiments, culminating in ex nihilo crystal structure prediction, which addresses the long-standing difficult problem of how to predict crystal structure polymorphs from nothing but a specified chemical composition. We present an overview of the capabilities of solid-state DFT simulations in all of these topics, illustrated with recent examples using the CASTEP computer program.
Thin bed responses and correction methods for cased hole density logging
Institute of Scientific and Technical Information of China (English)
Wu Wensheng; Zhang Yuling
2008-01-01
The study of the thin bed responses and correction methods in cased hole density logging can provide a theoretical basis for research to improve data processing methods. By using the Monte Carlo program MCNP, the change of detector count from thin beds with the vertical depth was calculated at different casing thicknesses. The calculation showed that with the low density thin bed moving upward,detector count first increased to a maximum then decreased. The responses of a thin bed with a high density were opposite to those of a thin bed with a low density. The change curve was symmetrical, and the maximums or minimums appeared at the midpoint between the detector and source. Besides, detector count increased with increasing thin bed thickness. At a specific thin bed thickness, further increase of thin bed thickness resulted in a slow increase of detector count then the count rate leveled off. In actual logging, the influence of adjacent formations on density log measurements can be ignored. Finally, based on numerical simulation correction methods for the dual influence of casing and thin beds are discussed.
Holes localized in nanostructures in an external magnetic field: g-factor and mixing of states
Energy Technology Data Exchange (ETDEWEB)
Semina, M. A.; Suris, R. A., E-mail: suris@theory.ioffe.ru [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)
2015-06-15
The energy spectrum and wave functions of holes in the valence band in semiconductor nanosystems, including quantum wells, quantum wires, and quantum dots, in an external magnetic field are theoretically investigated. The dependence of Zeeman splitting of the hole ground state upon variation in the size-quantization parameters with regard to the complex structure of the valence band and magnetic field-induced mixing of hole states is traced. Analytical formulas for describing the Zeeman effect in the valence band in the limiting cases of a quantum disk, spherically symmetric quantum dot, and quantum wire are presented. It is demonstrated that the g-factor of a hole is extremely sensitive to the hole-state composition (heavy or light hole) and, consequently, to the geometry of the size-quantization potential.
Milagro Limits and HAWC Sensitivity for the Rate-Density of Evaporating Primordial Black Holes
Abdo, A A; Alfaro, R; Allen, B T; Alvarez, C; Álvarez, J D; Arceo, R; Arteaga-Velázquez, J C; Aune, T; Solares, H A Ayala; Barber, A S; Baughman, B M; Bautista-Elivar, N; Gonzalez, J Becerra; Belmont, E; BenZvi, S Y; Berley, D; Rosales, M Bonilla; Braun, J; Caballero-Lopez, R A; Caballero-Mora, K S; Carramiñana, A; Castillo, M; Chen, C; Christopher, G E; Cotti, U; Cotzomi, J; de la Fuente, E; De León, C; DeYoung, T; Hernandez, R Diaz; Diaz-Cruz, L; Díaz-Vélez, J C; Dingus, B L; DuVernois, M A; Ellsworth, R W; Fiorino, D W; Fraija, N; Galindo, A; Garfias, F; González, M M; Goodman, J A; Grabski, V; Gussert, M; Hampel-Arias, Z; Harding, J P; Hays, E; Hoffman, C M; Hui, C M; Hüntemeyer, P; Imran, A; Iriarte, A; Karn, P; Kieda, D; Kolterman, B E; Kunde, G J; Lara, A; Lauer, R J; Lee, W H; Lennarz, D; Vargas, H León; Linares, E C; Linnemann, J T; Longo, M; Luna-GarcIa, R; MacGibbon, J H; Marinelli, A; Marinelli, S S; Martinez, H; Martinez, O; Martínez-Castro, J; Matthews, J A J; McEnery, J; Torres, E Mendoza; Mincer, A I; Miranda-Romagnoli, P; Moreno, E; Morgan, T; Mostafá, M; Nellen, L; Nemethy, P; Newbold, M; Noriega-Papaqui, R; Oceguera-Becerra, T; Patricelli, B; Pelayo, R; Pérez-Pérez, E G; Pretz, J; Rivière, C; Rosa-González, D; Ruiz-Velasco, E; Ryan, J; Salazar, H; Salesa, F; Sandoval, A; Parkinson, P M Saz; Schneider, M; Shoup, A; Silich, S; Sinnis, G; Smith, A J; Stump, D; Woodle, K Sparks; Springer, R W; Taboada, I; Toale, P A; Tollefson, K; Torres, I; Ukwatta, T N; Vasileiou, V; Villaseñor, L; Walker, G P; Weisgarber, T; Westerhoff, S; Williams, D A; Wisher, I G; Wood, J; Yodh, G B; Younk, P W; Zaborov, D; Zepeda, A; Zhou, H
2014-01-01
Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and can emit all species of fundamental particles thermally. PBHs with initial masses of ~5.0 x 10^14 g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV - TeV energy range, making them candidate Gamma-ray Burst (GRB) progenitors. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma-rays, the Milagro observatory is well suited for a direct search of PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a...
Milagro Limits and HAWC Sensitivity for the Rate-Density of Evaporating Primordial Black Holes
Abdo, A. A.; Abeysekara, A. U.; Alfaro, R.; Allen, B. T.; Alvarez, C.; Alvarez, J. D.; Arceo, R.; Arteaga-Velazquez, J. C.; Aune, T.; Ayala Solares, H. A.; Barber, A. S.; Baughman, B. M.; Bautista-Elivar, N.; Becerra Gonzalez, J.; Belmont, E.; BenZvi, S. Y.; Berley, D.; Rosales, M. Bonilla; Braun, J.; Hays, E.
2014-01-01
Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all species of fundamental particles thermally. PBHs with initial masses of approx.5.0 x 10(exp 14) g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV-TeV energy range. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a range of PBH observation times. In addition, we report the sensitivity of the Milagro successor, the High Altitude Water Cherenkov (HAWC) observatory, to PBH evaporation events.
Milagro limits and HAWC sensitivity for the rate-density of evaporating Primordial Black Holes
Abdo, A. A.; Abeysekara, A. U.; Alfaro, R.; Allen, B. T.; Alvarez, C.; Álvarez, J. D.; Arceo, R.; Arteaga-Velázquez, J. C.; Aune, T.; Ayala Solares, H. A.; Barber, A. S.; Baughman, B. M.; Bautista-Elivar, N.; Becerra Gonzalez, J.; Belmont, E.; BenZvi, S. Y.; Berley, D.; Bonilla Rosales, M.; Braun, J.; Caballero-Lopez, R. A.; Caballero-Mora, K. S.; Carramiñana, A.; Castillo, M.; Christopher, G. E.; Cotti, U.; Cotzomi, J.; de la Fuente, E.; De León, C.; DeYoung, T.; Diaz Hernandez, R.; Diaz-Cruz, L.; Díaz-Vélez, J. C.; Dingus, B. L.; DuVernois, M. A.; Ellsworth, R. W.; Fiorino, D. W.; Fraija, N.; Galindo, A.; Garfias, F.; González, M. M.; Goodman, J. A.; Grabski, V.; Gussert, M.; Hampel-Arias, Z.; Harding, J. P.; Hays, E.; Hoffman, C. M.; Hui, C. M.; Hüntemeyer, P.; Imran, A.; Iriarte, A.; Karn, P.; Kieda, D.; Kolterman, B. E.; Kunde, G. J.; Lara, A.; Lauer, R. J.; Lee, W. H.; Lennarz, D.; León Vargas, H.; Linares, E. C.; Linnemann, J. T.; Longo, M.; Luna-GarcIa, R.; MacGibbon, J. H.; Marinelli, A.; Marinelli, S. S.; Martinez, H.; Martinez, O.; Martínez-Castro, J.; Matthews, J. A. J.; McEnery, J.; Mendoza Torres, E.; Mincer, A. I.; Miranda-Romagnoli, P.; Moreno, E.; Morgan, T.; Mostafá, M.; Nellen, L.; Nemethy, P.; Newbold, M.; Noriega-Papaqui, R.; Oceguera-Becerra, T.; Patricelli, B.; Pelayo, R.; Pérez-Pérez, E. G.; Pretz, J.; Rivière, C.; Rosa-González, D.; Ruiz-Velasco, E.; Ryan, J.; Salazar, H.; Salesa, F.; Sandoval, A.; Saz Parkinson, P. M.; Schneider, M.; Silich, S.; Sinnis, G.; Smith, A. J.; Stump, D.; Sparks Woodle, K.; Springer, R. W.; Taboada, I.; Toale, P. A.; Tollefson, K.; Torres, I.; Ukwatta, T. N.; Vasileiou, V.; Villaseñor, L.; Weisgarber, T.; Westerhoff, S.; Williams, D. A.; Wisher, I. G.; Wood, J.; Yodh, G. B.; Younk, P. W.; Zaborov, D.; Zepeda, A.; Zhou, H.
2015-04-01
Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all species of fundamental particles thermally. PBHs with initial masses of ∼5.0 × 1014 g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV-TeV energy range. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a range of PBH observation times. In addition, we report the sensitivity of the Milagro successor, the High Altitude Water Cherenkov (HAWC) observatory, to PBH evaporation events.
The mass density in black holes inferred from the X-ray background
Fabian, A C
1999-01-01
The X-ray Background (XRB) probably originates from the integrated X-ray emission of active galactic nuclei (AGN). Modelling of its flat spectrum implies considerable absorption in most AGN. Compton down-scattering means that sources in which the absorption is Compton thick are unlikely to be major contributors to the background intensity so the observed spectral intensity at about 30 keV is little affected by photoelectric absorption. Assuming that the intrinsic photon index of AGN is 2, we then use the 30 keV intensity of the XRB to infer the absorption-corrected energy density of the background. Soltan's argument then enables us to convert this to a mean local density in black holes, assuming an accretion efficiency of 0.1 and a mean AGN redshift of 2. The result is within a factor of two of that estimated by Haehnelt et al from the optically-determined black hole masses of Magorrian et al. We conclude that there is no strong need for any radiatively inefficient mode of accretion for building the masses of...
Milagro Limits and HAWC Sensitivity for the Rate-Density of Evaporating Primordial Black Holes
Abdo, A. A.; Abeysekara, A. U.; Alfaro, R.; Allen, B. T.; Alvarez, C.; Alvarez, J. D.; Arceo, R.; Arteaga-Velazquez, J. C.; Aune, T.; Ayala Solares, H. A.;
2014-01-01
Primordial Black Holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all species of fundamental particles thermally. PBHs with initial masses of approx.5.0 x 10(exp 14) g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV-TeV energy range. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. Based on a search on the Milagro data, we report new PBH burst rate density upper limits over a range of PBH observation times. In addition, we report the sensitivity of the Milagro successor, the High Altitude Water Cherenkov (HAWC) observatory, to PBH evaporation events.
Effect of flexural phonons on the hole states in single-layer black phosphorus
Brener, S.; Rudenko, A. N.; Katsnelson, M. I.
2017-01-01
Flexural thermal fluctuations in crystalline membranes affect the band structure of the carriers, which leads to an exponential density-of-states (DOS) tail beyond the unperturbed band edge. We present a theoretical description of this tail for a particular case of holes in single-layer black phosphorus, a material which exhibits an extremely anisotropic quasi-one-dimensional dispersion (my/mx≫1 ) and, as a result, an enhanced Van Hove singularity at the valence band top. The material parameters are determined by ab initio calculations and then are used for quantitative estimation of the effect of two-phonon (flexural) processes have on the charge carrier DOS. It is shown that unlike the isotropic case, the physics is determined by the phonons with wave vectors of the order of q*, where q* determines the crossover between harmonic and anharmonic behavior of the flexural phonons. The spectral density of the holes in single-layer black phosphorus at finite temperatures is calculated.
Electromagnetic local density of states in graphene-covered porous silicon carbide
Energy Technology Data Exchange (ETDEWEB)
Zhou, Ting [Department of Physics, Nanchang University, Nanchang 330031 (China); Wang, Tong-Biao, E-mail: tbwang@ncu.edu.cn [Department of Physics, Nanchang University, Nanchang 330031 (China); Liao, Qing-Hua; Liu, Jiang-Tao; Yu, Tian-Bao [Department of Physics, Nanchang University, Nanchang 330031 (China); Liu, Nian-Hua [Institute for Advanced Study, Nanchang University, Nanchang 330031 (China)
2017-06-21
Surface phonon polariton supported by silicon carbide (SiC) can be strongly coupled with graphene plasmon in the graphene-covered SiC bulk. The spectrum of the electromagnetic local density of states exhibits two peaks whose positions can be tuned by the chemical potential of graphene. In this work, we study the electromagnetic local density of states in the proximity of a graphene-covered SiC with periodic hole arrays. The well-known peak from the coupling of surface polariton supported by SiC and graphene plasmon splits into two. With increased volume ratio of holes, one of the split peak shifts towards high frequencies, whereas the other moves towards low frequencies. The dependence of split-peak positions on the chemical potential and permittivity of filling materials in the holes are also investigated. This study offers another method of modulating the electromagnetic local density of states. - Highlights: • The electromagnetic local density of states in the proximity of graphene-covered anisotropic SiC is firstly studied. • The peak from resonance of surface phonon polaritons in the EM-LDOS spectrum can be split into two. • The split peaks can be tuned by chemical potential, filling factor, and filling materials. • Our results provide a new method to modulate the EM-LDOS.
Gorczak, Natalie; Tarkuç, Simge; Renaud, Nicolas; Houtepen, Arjan J; Eelkema, Rienk; Siebbeles, Laurens D A; Grozema, Ferdinand C
2014-06-05
We report measurements of hole and electron transfer along identical oligo-p-phenylene molecular bridges of increasing length. Although the injection barriers for hole and electron transfer are similar, we observed striking differences in the distance dependence and absolute magnitude of the rates of these two processes. Electron transfer is characterized by an almost distance-independent, fast charge-transfer rate. Hole transfer presents a much slower rate that decreases significantly with the length of the bridge. Time-dependent density functional calculations show that the observed differences can be explained by the delocalization of the respective initial excitation. The evaluation of the initial state is therefore essential when comparing charge-transfer rates between different donor-bridge-acceptor systems.
Density of States for Warped Energy Bands
Mecholsky, Nicholas A.; Resca, Lorenzo; Pegg, Ian L.; Fornari, Marco
2016-02-01
Warping of energy bands can affect the density of states (DOS) in ways that can be large or subtle. Despite their potential for significant practical impacts on materials properties, these effects have not been rigorously demonstrated previously. Here we rectify this using an angular effective mass formalism that we have developed. To clarify the often confusing terminology in this field, “band warping” is precisely defined as pertaining to any multivariate energy function E(k) that does not admit a second-order differential at an isolated critical point in k-space, which we clearly distinguish from band non-parabolicity. We further describe band “corrugation” as a qualitative form of band warping that increasingly deviates from being twice differentiable at an isolated critical point. These features affect the density-of-states and other parameters ascribed to band warping in various ways. We demonstrate these effects, providing explicit calculations of DOS and their effective masses for warped energy dispersions originally derived by Kittel and others. Other physical and mathematical examples are provided to demonstrate fundamental distinctions that must be drawn between DOS contributions that originate from band warping and contributions that derive from band non-parabolicity. For some non-degenerate bands in thermoelectric materials, this may have profound consequences of practical interest.
Steady state relativistic stellar dynamics around a massive black hole
Bar-Or, Ben
2015-01-01
A massive black hole (MBH) consumes stars whose orbits evolve into the small phase-space volume of unstable orbits, the "loss-cone", which take them directly into the MBH, or close enough to interact strongly with it. The resulting phenomena: tidal heating and tidal disruption, binary capture and hyper-velocity star ejection, gravitational wave (GW) emission by inspiraling compact remnants, or hydrodynamical interactions with an accretion disk, are of interest as they can produce observable signatures and thereby reveal the existence of the MBH, affect its mass and spin evolution, probe strong gravity, and provide information on stars and gas near the MBH. The continuous loss of stars and the processes that resupply them shape the central stellar distribution. We investigate relativistic stellar dynamics near the loss-cone of a non-spinning MBH in steady-state analytically and by Monte Carlo simulations of the diffusion of the orbital parameters. These take into account Newtonian mass precession due to enclos...
Stornaiolo, C
2002-01-01
In this letter we propose the existence of low density black holes and discuss its compatibility with the cosmological observations. The origin of these black holes can be traced back to the collapse of long wavelength cosmological perturbations during the matter dominated era, when the densities are low enough to neglect any internal and thermal pressure. By introducing a threshold density $\\hat{\\rho}$ above which pressure and non-gravitational interactions become effective, we find the highest wavelength for the perturbations that can reach an equilibrium state instead of collapsing to a black hole. The low density black holes introduced here, if they exist, can be observed through weak and strong gravitational lensing effects. Finally we observe that we obtained here a cosmological model which is capable to explain in a qualitative way the void formation together with the value $\\Omega=1$. But we remark that it needs to be improved by considering non spherical symmetric black holes.
Milagro Limits and HAWC Sensitivity for the Rate Density of Evaporating Primordial Black Holes
Marinelli, Samuel; HAWC Collaboration; Milagro Collaboration
2015-04-01
Primordial black holes (PBHs) are gravitationally collapsed objects that may have been created by density fluctuations in the early universe and could have arbitrarily small masses down to the Planck scale. Hawking showed that due to quantum effects, a black hole has a temperature inversely proportional to its mass and will emit all energetically allowed species of fundamental particles thermally. PBHs with initial masses of order 5 . 0 ×1010 g should be expiring in the present epoch with bursts of high-energy particles, including gamma radiation in the GeV - TeV energy range. The Milagro high-energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma-ray spectrum. Due to its large field of view, more than 90% duty cycle, and sensitivity up to 100-TeV gamma rays, the Milagro observatory is well suited to perform a search for PBH bursts. A search of five years of Milagro data yielded no detections at 5 σ and set a local (parsec-scale) upper limit of 3 . 6 ×104 PBH bursts/year/pc3. In addition, we will report the sensitivity of the Milagro successor, the High-Altitude Water-Cherenkov (HAWC) observatory, to PBH evaporation events. This work was supported by the National Science Foundation.
Black hole state counting in LQG: A number theoretical approach
Agullo, Ivan; Diaz-Polo, Jacobo; Fernandez-Borja, Enrique; Villaseñor, Eduardo J S
2008-01-01
We give a practical method to exactly compute black hole entropy in the framework of Loop Quantum Gravity. Along the way we provide a complete characterization of the relevant sector of the spectrum of the area operator, including degeneracies, and determine the number of solutions to the projection constraint analytically. We use a computer implementation of the proposed algorithm to confirm and extend previous results on the detailed structure of the black hole degeneracy spectrum.
Comments on non-Gaussian density perturbations and the production of primordial black holes
Bullock, J S; Bullock, James S.; Primack, Joel R.
1998-01-01
We review the basic arguments for the likelihood of non-Gaussian density perturbations in inflation models with primordial black hole (PBH) production. We discuss our derived distributions of field fluctuations and their implications, specifically commenting on the fine-tuning problem. We also discuss how the derived distributions may be affected when linked to metric perturbations. While linking the metric perturbations to field fluctuations in a nonlinear way may be important for determining exact probability distributions, the correct mapping is not self-evident. The calculation of P. Ivanov, which yields skew positive distribution, is based on an ansatz for the behavior of the nonlinear metric perturbation. We note that the ``natural'' generalization of the gauge-invariant formalism favored by Bond and Salopek yields an effective linear link between the distribution of field fluctuations and metric perturbations during inflation.
Directory of Open Access Journals (Sweden)
Bai Shiye
2016-05-01
Full Text Available An objective function defined by minimum compliance of topology optimization for 3D continuum structure was established to search optimal material distribution constrained by the predetermined volume restriction. Based on the improved SIMP (solid isotropic microstructures with penalization model and the new sensitivity filtering technique, basic iteration equations of 3D finite element analysis were deduced and solved by optimization criterion method. All the above procedures were written in MATLAB programming language, and the topology optimization design examples of 3D continuum structure with reserved hole were examined repeatedly by observing various indexes, including compliance, maximum displacement, and density index. The influence of mesh, penalty factors, and filter radius on the topology results was analyzed. Computational results showed that the finer or coarser the mesh number was, the larger the compliance, maximum displacement, and density index would be. When the filtering radius was larger than 1.0, the topology shape no longer appeared as a chessboard problem, thus suggesting that the presented sensitivity filtering method was valid. The penalty factor should be an integer because iteration steps increased greatly when it is a noninteger. The above modified variable density method could provide technical routes for topology optimization design of more complex 3D continuum structures in the future.
Ground state of high-density matter
Copeland, ED; Kolb, Edward W.; Lee, Kimyeong
1988-01-01
It is shown that if an upper bound to the false vacuum energy of the electroweak Higgs potential is satisfied, the true ground state of high-density matter is not nuclear matter, or even strange-quark matter, but rather a non-topological soliton where the electroweak symmetry is exact and the fermions are massless. This possibility is examined in the standard SU(3) sub C tensor product SU(2) sub L tensor product U(1) sub Y model. The bound to the false vacuum energy is satisfied only for a narrow range of the Higgs boson masses in the minimal electroweak model (within about 10 eV of its minimum allowed value of 6.6 GeV) and a somewhat wider range for electroweak models with a non-minimal Higgs sector.
GRS 1758–258: RXTE Monitoring of a Rare Persistent Hard State Black Hole
Directory of Open Access Journals (Sweden)
M. Obst
2011-01-01
Full Text Available GRS 1758–258 is the least studied of the three persistent black hole X-ray binaries in our Galaxy. It is also one of only two known black hole candidates, including all black hole transients, which shows a decrease of its 3-10 keV flux when entering the thermally dominated soft state, rather than an increase.We present the spectral evolution of GRS 1758–258 from RXTE-PCA observations spanning a time of about 11 years from 1996 to 2007. During this time, seven dim soft states are detected. We also consider INTEGRAL monitoring observations of the source and compare the long-term behavior to that of the bright persistent black hole X-ray binary Cygnus X-1. We discuss the observed state transitions in the light of physical scenarios for black hole transitions.
Foucart, F.; Desai, D.; Brege, W.; Duez, M. D.; Kasen, D.; Hemberger, D. A.; Kidder, L. E.; Pfeiffer, H. P.; Scheel, M. A.
2017-02-01
Neutron star-black hole binaries are among the strongest sources of gravitational waves detectable by current observatories. They can also power bright electromagnetic signals (gamma-ray bursts, kilonovae), and may be a significant source of production of r-process nuclei. A misalignment of the black hole spin with respect to the orbital angular momentum leads to precession of that spin and of the orbital plane, and has a significant effect on the properties of the post-merger remnant and of the material ejected by the merger. We present a first set of simulations of precessing neutron star-black hole mergers using a hot, composition dependent, nuclear-theory based equation of state (DD2). We show that the mass of the remnant and of the dynamical ejecta are broadly consistent with the result of simulations using simpler equations of state, while differences arise when considering the dynamics of the merger and the velocity of the ejecta. We show that the latter can easily be understood from assumptions about the composition of low-density, cold material in the different equations of state, and propose an updated estimate for the ejecta velocity which takes those effects into account. We also present an updated mesh-refinement algorithm which allows us to improve the numerical resolution used to evolve neutron star-black hole mergers.
Three-charge black holes and quarter BPS states in Little String Theory
Energy Technology Data Exchange (ETDEWEB)
Giveon, Amit [Racah Institute of Physics, The Hebrew University,Jerusalem, 91904 (Israel); Harvey, Jeffrey; Kutasov, David; Lee, Sungjay [Enrico Fermi Institute and Department of Physics, The University of Chicago,5620 S. Ellis Av., Chicago, Illinois 60637 (United States)
2015-12-22
We show that the system of k NS5-branes wrapping T{sup 4}×S{sup 1} has non-trivial vacuum structure. Different vacua have different spectra of 1/4 BPS states that carry momentum and winding around the S{sup 1}. In one vacuum, such states are described by black holes; in another, they can be thought of as perturbative BPS states in Double Scaled Little String Theory. In general, both kinds of states are present. We compute the degeneracy of perturbative BPS states exactly, and show that it differs from that of the corresponding black holes. We comment on the implication of our results to the black hole microstate program, UV/IR mixing in Little String Theory, string thermodynamics, the string/black hole transition, and other issues.
Analytic continuation of the rotating black hole state counting
Achour, Jibril Ben; Perez, Alejandro
2016-01-01
In loop quantum gravity, a spherical black hole can be described in terms of a Chern-Simons theory on a punctured 2-sphere. The sphere represents the horizon. The punctures are the edges of spin-networks in the bulk which cross the horizon and carry quanta of area. One can generalize this construction and model a rotating black hole by adding an extra puncture colored with the angular momentum J in the 2-sphere. We compute the entropy of rotating black holes in this model and study its semi-classical limit. After performing an analytic continuation which sends the Barbero-Immirzi parameter to +/- i, we show that the leading order term in the semi-classical expansion of the entropy reproduces the Bekenstein-Hawking law independently of the value of J.
Detailed black hole state counting in loop quantum gravity
Agullo, Ivan; Barbero G., J. Fernando; Borja, Enrique F.; Diaz-Polo, Jacobo; Villaseñor, Eduardo J. S.
2010-10-01
We give a complete and detailed description of the computation of black hole entropy in loop quantum gravity by employing the most recently introduced number-theoretic and combinatorial methods. The use of these techniques allows us to perform a detailed analysis of the precise structure of the entropy spectrum for small black holes, showing some relevant features that were not discernible in previous computations. The ability to manipulate and understand the spectrum up to the level of detail that we describe in the paper is a crucial step toward obtaining the behavior of entropy in the asymptotic (large horizon area) regime.
Detailed black hole state counting in loop quantum gravity
Agullo, Ivan; Borja, Enrique F; Diaz-Polo, Jacobo; Villaseñor, Eduardo J S; 10.1103/PhysRevD.82.084029
2011-01-01
We give a complete and detailed description of the computation of black hole entropy in loop quantum gravity by employing the most recently introduced number-theoretic and combinatorial methods. The use of these techniques allows us to perform a detailed analysis of the precise structure of the entropy spectrum for small black holes, showing some relevant features that were not discernible in previous computations. The ability to manipulate and understand the spectrum up to the level of detail that we describe in the paper is a crucial step towards obtaining the behavior of entropy in the asymptotic (large horizon area) regime.
Oil Well Top Hole Locations, State-oil-08-08, Published in 2008, Duchesne County.
NSGIC GIS Inventory (aka Ramona) — This Oil Well Top Hole Locations dataset, was produced all or in part from Other information as of 2008. It is described as 'State-oil-08-08'. Data by this publisher...
Oil Shale Core Holes Containing Nahcolite in the State of Colorado
U.S. Geological Survey, Department of the Interior — This file contains points that describe locations of oil shale core holes that contain nahcolite in the state of Colorado and is available as an ESRI shapefile,...
Unitarity of black hole evaporation in final-state projection models
Lloyd, Seth; Preskill, John
2014-08-01
Almheiri et al. have emphasized that otherwise reasonable beliefs about black hole evaporation are incompatible with the monogamy of quantum entanglement, a general property of quantum mechanics. We investigate the final-state projection model of black hole evaporation proposed by Horowitz and Maldacena, pointing out that this model admits cloning of quantum states and polygamous entanglement, allowing unitarity of the evaporation process to be reconciled with smoothness of the black hole event horizon. Though the model seems to require carefully tuned dynamics to ensure exact unitarity of the black hole S-matrix, for a generic final-state boundary condition the deviations from unitarity are exponentially small in the black hole entropy; furthermore observers inside black holes need not detect any deviations from standard quantum mechanics. Though measurements performed inside old black holes could potentially produce causality-violating phenomena, the computational complexity of decoding the Hawking radiation may render the causality violation unobservable. Final-state projection models illustrate how inviolable principles of standard quantum mechanics might be circumvented in a theory of quantum gravity.
Density of States Simulations of Confined Glasses
Faller, Roland; Ghosh, Jayeeta
2008-03-01
Glassy systems under confinement have been studied with great enthusiasm and effort for the last decades. They are relevant both fundamentally and technically because there is still debate about the nature of glass transition in small geometries which is important for lithographic processes in the semiconductor and other industries. In this work we are using the Wang-Landau approach also known as Density of States Monte Carlo to study glassy systems in bulk and under confinement. We apply the technique to a model binary Lennard Jones glass as well as the small organic glass former Ortho-terphenyl (OTP). For Lennard Jones glasses we use a well tested model. For OTP we start from a united atom model and then derive systematically a coarse grained representation by replacing each phenyl ring with a bead and using the Iterative Boltzmann Inversion. The properties of bulk Lennard Jones model show very good agreement with literature values. The atomistic and coarse grained representations of ortho-terphenyl in the bulk are in good agreement with experiments. Unsupported freestanding films show a lower glass transition than the bulk value.
Hole states in diamond p-delta-doped field effect transistors
Energy Technology Data Exchange (ETDEWEB)
Martinez-Orozco, J C; Rodriguez-Vargas, I [Unidad Academica de Fisica, Universidad Autonoma de Zacatecas, Calzada Solidaridad Esquina con Paseo la Bufa S/N, CP 98060 Zacatecas, ZAC. (Mexico); Mora-Ramos, M E, E-mail: jcmover@correo.unam.m [Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, CP 62209 Cuernavaca, MOR. (Mexico)
2009-05-01
The p-delta-doping in diamond allows to create high density two-dimensional hole gases. This technique has already been applied in the design and fabrication of diamond-based field effect transistors. Consequently, the knowledge of the electronic structure is of significant importance to understand the transport properties of diamond p-delta-doped systems. In this work the hole subbands of diamond p-type delta-doped quantum wells are studied within the framework of a local-density Thomas-Fermi-based approach for the band bending profile. The calculation incorporates an independent three-hole-band scheme and considers the effects of the contact potential, the delta-channel to contact distance, and the ionized impurity density.
Ghaffarnejad, H; Mojahedi, M A
2013-01-01
We obtain renormalized stress tensor of a mass-less, charge-less dynamical quantum scalar field, minimally coupled with a spherically symmetric static Lukewarm black hole. In two dimensional analog the minimal coupling reduces to the conformal coupling and the stress tensor is found to be determined by the nonlocal contribution of the anomalous trace and some additional parameters in close relation to the work presented by Christensen and Fulling. Lukewarm black holes are a special class of Reissner- Nordstr\\"{o}m-de Sitter space times where its electric charge is equal to its mass. Having the obtained renormalized stress tensor we attempt to obtain a time-independent solution of the well known metric back reaction equation. Mathematical derivations predict that the final state of an evaporating quantum Lukewarm black hole reduces to a remnant stable mini black hole with moved locations of the horizons. Namely the perturbed black hole (cosmological) horizon is compressed (extended) to scales which is smaller ...
Ohsuga, Ken; Mori, Masao; Kato, Yoshiaki
2009-01-01
Black-hole accretion systems are known to possess several distinct modes (or spectral states), such as low/hard state, high/soft state, and so on. Since the dynamics of the corresponding flows is distinct, theoretical models were separately discussed for each state. We here propose a unified model based on our new, global, two-dimensional radiation-magnetohydrodynamic simulations. By controlling a density normalization we could for the first time reproduce three distinct modes of accretion flow and outflow with one numerical code. When the density is large (model A), a geometrically thick, very luminous disk forms, in which photon trapping takes place. When the density is moderate (model B), the accreting gas can effectively cool by emitting radiation, thus generating a thin disk, i.e., the soft-state disk. When the density is too low for radiative cooling to be important (model C), a disk becomes hot, thick, and faint; i.e., the hard-state disk. The magnetic energy is amplified within the disk up to about tw...
Equation of state for a classical gas of BPS black holes
Kan, N; Shiraishi, K; Kan, Nahomi; Maki, Takuya; Shiraishi, Kiyoshi
2001-01-01
A point particle treatment to the statistical mechanics of BPS black holes in Einstein-Maxwell-dilaton theory is developed. Because of the absence of the static potential, the canonical partition function for $N$ BPS black holes can be expressed by the volume of the moduli space for them. We estimate the equation of state for a classical gas of BPS black holes by Pad\\'e approximation and find that the result agrees with the one obtained by the mean-field approximation.
Phase contrast imaging of high-intensity laser hole boring of solid-density wires at LCLS-MEC
Schumaker, W.; Brown, S.; Curry, C.; Gauthier, M.; Gamboa, E.; Goede, S.; Fletcher, L.; Kim, J.; MacDonald, M.; Mishra, R.; Roedel, C.; Glenzer, S.; Fiuza, F.; Granados, E.; Nagler, B.; Zhou, Z.; MacKinnon, A.; Obst, L.; Ziel, K.; Pak, A.; Williams, G.; Fajardo, M.
2016-10-01
High-intensity, relativistic (a0 > 1) laser plasma interactions on solid surfaces produce a rich mix of dynamics on the laser timescale (Weibel instabilities, surface effects, sheath formation, etc.) and hydrodynamic timescale (hole-boring, shocks, etc.). Probing these interactions optically is difficult due to critical density layer obscuring the surface of the target, whereas probing with hard X-rays from K-alpha sources does not sufficiently resolve these interactions temporally as they are typically many ps in duration. Presented here are the first experimental measurements of laser hole-boring on a carbon wire surfaces performed at the LCLS-MEC facility. With laser intensities of up to 1019 W / cm2 , we observe the dissociation of micron-sized wires over 100 ps timescale with peak hole boring velocities up to 0.001 c using phase-contrast imaging. This work was funded by DOE FES under FWP #100182.
Charge carrier density dependence of the hole mobility in poly(p-phenylene vinylene)
Tanase, C; Blom, PWM; de Leeuw, DM; Meijer, EJ
2004-01-01
The hole transport in various poly(p-phenylene vinylene) (PPV) derivatives has been investigated in field-effect transistors (FETs) and light-emitting diodes (LEDs) as a function of temperature and applied bias. The discrepancy between the experimental hole mobilities extracted from FETs and LEDs ba
Schindler, Jan-Torge; Fan, Xiaohui; Duschl, Wolfgang J.
2016-01-01
At redshifts beyond $z{\\sim}1$ measuring the black hole galaxy relations proves to be a difficult task. The bright light of the AGN aggravates deconvolution of black hole and galaxy properties. On the other hand high redshift data on these relations is vital to understand in what ways galaxies and black holes co-evolve and in what ways they don't. In this work we use black hole (BHMDs) and stellar mass densities (SMDs) to constrain the possible co-evolution of black holes with their host gala...
Neutron spectroscopic factors of 55Ni hole-states from (p,d transfer reactions
Directory of Open Access Journals (Sweden)
A. Sanetullaev
2014-09-01
Full Text Available Spectroscopic information has been extracted on the hole-states of 55Ni, the least known of the quartet of nuclei (55Ni, 57Ni, 55Co and 57Cu, one nucleon away from 56Ni, the N=Z=28 double magic nucleus. Using the H1(Ni56,dNi55 transfer reaction in inverse kinematics, neutron spectroscopic factors, spins and parities have been extracted for the f7/2, p3/2 and the s1/2 hole-states of 55Ni. These new data provide a benchmark for large basis calculations that include nucleonic orbits in both the sd and pf shells. State of the art calculations have been performed to describe the excitation energies and spectroscopic factors of the s1/2 hole-state below Fermi energy.
Neutron spectroscopic factors of {sup 55}Ni hole-states from (p,d) transfer reactions
Energy Technology Data Exchange (ETDEWEB)
Sanetullaev, A. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Tsang, M.B., E-mail: tsang@nscl.msu.edu [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Lynch, W.G.; Lee, Jenny; Bazin, D. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Chan, K.P. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Physics Department, Hong Kong Chinese University, Shatin, Hong Kong (China); Coupland, D.; Henzl, V.; Henzlova, D.; Kilburn, M.; Rogers, A.M. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Sun, Z.Y. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Institute of Modern Physics, CAS, Lanzhou 730000 (China); Youngs, M. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Charity, R.J.; Sobotka, L.G. [Department of Chemistry, Washington University, St. Louis, MO 63130 (United States); Famiano, M. [Department of Physics, Western Michigan University, Kalamazoo, MI 49008 (United States); Hudan, S. [Department of Chemistry, Indiana University, Bloomington, IN 47405 (United States); Shapira, D. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Peters, W.A. [Rutgers University, Piscataway, NJ 08854 (United States); Barbieri, C. [Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); and others
2014-09-07
Spectroscopic information has been extracted on the hole-states of {sup 55}Ni, the least known of the quartet of nuclei ({sup 55}Ni, {sup 57}Ni, {sup 55}Co and {sup 57}Cu), one nucleon away from {sup 56}Ni, the N=Z=28 double magic nucleus. Using the {sup 1}H({sup 56}Ni,d){sup 55}Ni transfer reaction in inverse kinematics, neutron spectroscopic factors, spins and parities have been extracted for the f{sub 7/2}, p{sub 3/2} and the s{sub 1/2} hole-states of {sup 55}Ni. These new data provide a benchmark for large basis calculations that include nucleonic orbits in both the sd and pf shells. State of the art calculations have been performed to describe the excitation energies and spectroscopic factors of the s{sub 1/2} hole-state below Fermi energy.
Neutron spectroscopic factors of $^{55}$Ni hole-states from (p,d) transfer reactions
Sanetullaev, A; Lynch, W G; Lee, Jenny; Bazin, D; Chan, K P; Coupland, D; Henzl, V; Henzlova, D; Kilburn, M; Rogers, A M; Sun, Z Y; Youngs, M; Charity, R J; Sobotka, L G; Famiano, M; Hudan, S; Shapira, D; Peters, W A; Barbieri, C; Hjorth-Jensen, M; Horoi, M; Otsuka, T; Suzuki, T; Utsuno, Y
2014-01-01
Spectroscopic information has been extracted on the hole-states of $^{55}$Ni, the least known of the quartet of nuclei ($^{55}$Ni, $^{57}$Ni, $^{55}$Co and $^{57}$Co), one neutron away from $^{56}$Ni, the N=Z=28 double magic nucleus. Using the $^{1}$H($^{56}$Ni,d)$^{55}$Ni transfer reaction in inverse kinematics, neutron spectroscopic factors, spins and parities have been extracted for the f$_{7/2}$, p$_{3/2}$ and the s$_{1/2}$ hole-states of $^{55}$Ni. This new data provides a benchmark for large basis calculations that include nucleonic orbits in both the sd and pf shells. State of the art calculations have been performed to describe the excitation energies and spectroscopic factors of the s$_{1/2}$ hole-state below Fermi energy.
Neutron spectroscopic factors of 55Ni hole-states from (p,d) transfer reactions
Sanetullaev, A.; Tsang, M. B.; Lynch, W. G.; Lee, Jenny; Bazin, D.; Chan, K. P.; Coupland, D.; Henzl, V.; Henzlova, D.; Kilburn, M.; Rogers, A. M.; Sun, Z. Y.; Youngs, M.; Charity, R. J.; Sobotka, L. G.; Famiano, M.; Hudan, S.; Shapira, D.; Peters, W. A.; Barbieri, C.; Hjorth-Jensen, M.; Horoi, M.; Otsuka, T.; Suzuki, T.; Utsuno, Y.
2014-09-01
Spectroscopic information has been extracted on the hole-states of 55Ni, the least known of the quartet of nuclei (55Ni, 57Ni, 55Co and 57Cu), one nucleon away from 56Ni, the N=Z=28 double magic nucleus. Using the H1(Ni56,d)Ni55 transfer reaction in inverse kinematics, neutron spectroscopic factors, spins and parities have been extracted for the f7/2, p3/2 and the s1/2 hole-states of 55Ni. These new data provide a benchmark for large basis calculations that include nucleonic orbits in both the sd and pf shells. State of the art calculations have been performed to describe the excitation energies and spectroscopic factors of the s1/2 hole-state below Fermi energy.
Wang, Dong; Wang, Haifeng; Hu, P
2015-01-21
Using density functional theory calculations with HSE 06 functional, we obtained the structures of spin-polarized radicals on rutile TiO2(110), which is crucial to understand the photooxidation at the atomic level, and further calculate the thermodynamic stabilities of these radicals. By analyzing the results, we identify the structural features for hole trapping in the system, and reveal the mutual effects among the geometric structures, the energy levels of trapped hole states and their hole trapping capacities. Furthermore, the results from HSE 06 functional are compared to those from DFT + U and the stability trend of radicals against the number of slabs is tested. The effect of trapped holes on two important steps of the oxygen evolution reaction, i.e. water dissociation and the oxygen removal, is investigated and discussed.
Mihaila, Bogdan; Heisenberg, Jochen
2000-04-01
We continue the investigations of ground state properties of closed-shell nuclei using the Argonne v18 realistic NN potential, together with the Urbana IX three-nucleon interaction. The ground state wave function is used to calculate the charge form factor and charge density. Starting with the ground state wave function of the closed-shell nucleus, we use the equation of motion technique to calculate the ground state and excited states of a neighboring nucleus. We then generate the corresponding magnetic form factor. We correct for distortions due to the interaction between the electron probe and the nuclear Coulomb field using the DWBA picture. We compare our results with the available experimental data. Even though our presentation will focus mainly on the ^16O and ^15N nuclei, results for other nuclei in the p and s-d shell will also be presented.
Shape transition of state density for bosonic systems
Indian Academy of Sciences (India)
Harshal N Deota; N D Chavda; V Potbhare
2013-12-01
For a finite boson system, the ensemble-averaged state density has been computed with respect to the body interaction rank . The shape of such a state density changes from Gaussian to semicircle as the body rank of the interaction increases. This state density is expressed as a linear superposition of Gaussian and semicircular states. The nearest-neighbour spacing distribution (NNSD), which is one of the most important spectral properties of a system, is studied. The NNSDs are rather independent of body rank and show a Wigner distribution throughout.
The effects of high density on the X-ray spectrum reflected from accretion discs around black holes
García, Javier A.; Fabian, Andrew C.; Kallman, Timothy R.; Dauser, Thomas; Parker, Michael L.; McClintock, Jeffrey E.; Steiner, James F.; Wilms, Jörn
2016-10-01
Current models of the spectrum of X-rays reflected from accretion discs around black holes and other compact objects are commonly calculated assuming that the density of the disc atmosphere is constant within several Thomson depths from the irradiated surface. An important simplifying assumption of these models is that the ionization structure of the gas is completely specified by a single, fixed value of the ionization parameter ξ, which is the ratio of the incident flux to the gas density. The density is typically fixed at ne = 1015 cm-3. Motivated by observations, we consider higher densities in the calculation of the reflected spectrum. We show by computing model spectra for ne ≳ 1017 cm-3 that high-density effects significantly modify reflection spectra. The main effect is to boost the thermal continuum at energies ≲ 2 keV. We discuss the implications of these results for interpreting observations of both active galactic nuclei and black hole binaries. We also discuss the limitations of our models imposed by the quality of the atomic data currently available.
A complex state transition from the black hole candidate Swift J1753.5-0127
Soleri, P; Motta, S; Belloni, T; Casella, P; Méndez, M; Altamirano, D; Linares, M; Wijnands, R; Fender, R; van der Klis, M
2012-01-01
We present our monitoring campaign of the outburst of the black-hole candidate Swift J1753.5-0127, observed with the Rossi X-ray Timing Explorer and the Swift satellites. After ~4.5 years since its discovery, the source had a transition to the hard intermediate state. We performed spectral and timing studies of the transition showing that, unlike the majority of the transient black holes, the system did not go to the soft states but it returned to the hard state after a few months. During this transition Swift J1753.5-0127 features properties which are similar to those displayed by the black hole Cygnus X-1. We compared Swift J1753.5-0127 to one dynamically confirmed black hole and two neutron stars showing that its power spectra are in agreement with the binary hosting a black hole. We also suggest that the prolonged period at low flux that followed the initial flare is reminiscent of that observed in other X-ray binaries, as well as in cataclysmic variables.
Density of states in an electrically biased quantum well
Indian Academy of Sciences (India)
A Khan; S Sinha; P Panchadhyayee
2007-10-01
Density of states in a quantum well has been studied in the presence of an electric ﬁeld applied perpendicular to the growth direction. We have shown that an extra quantization is introduced to the motion of the electron due to the discrete energy levels known as Wannier–Stark ladder states and the nature of density of electronic states changes from quasi two-dimensional to quasi one-dimensional.
Density of Ni-Cr Alloy in the Mushy State
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
The density of Ni-Cr alloy in the mushy state has been measured using the modified sessile drop method. The density of Ni-Cr alloy in the mushy state was found to decrease with increasing temperature and Cr concentration in alloy.The molar volume of Ni-Cr alloy in the mushy state therefore increases with increasing the Cr concentration in alloy.The ratio of the difference of density divided by the temperature difference between liquidus and solidus temperatures decreases with increasing Cr concentration. The density of the alloy increased with the precipitation of a solid phase in alloy during the solidification process. The temperature dependence of the density of alloy in the mushy state was not linear but biquadratic.
Neutron-hole states in 45Ar from p(46Ar,d)45Ar reactions
Lu, F; Tsang, M B; Bazin, D; Coupland, D; Henzl, V; Henzlova, D; Kilburn, M; Lynch, W G; Rogers, A M; Sanetullaev, A; Sun, Z Y; Youngs, M; Charity, R J; Sobotka, L G; Famiano, M; Hudan, S; Horoi, M; Ye, Y L
2013-01-01
To improve the effective interactions in the pf shell, it is important to measure the single particle- and hole- states near the N=28 shell gap. In this paper, the neutron spectroscopic factors of hole-states from the unstable neutron-rich 45Ar (Z=18, N=27) nucleus have been studied using 1H(46Ar, 2H)45Ar transfer reaction in inverse kinematics. Comparison of our results with the particle-states of 45Ar produced in 2H(44Ar, H)45Ar reaction shows that the two reactions populate states with different angular momentum. Using the angular distributions, we are able to confirm the spin assignments of four low-lying states of 45Ar. These are the ground state (f7/2), the first-excited (p3/2), the s1/2 and the d3/2 states. While large basis shell model predictions describe spectroscopic properties of the ground and p3/2 states very well, they fail to describe the s1/2 and d3/2 hole-states.
Two spectral states of the black-hole candidate GX 339-4
Lavrov, S. V.; Borozdin, K. N.; Aleksandrovich, N. L.; Aref'ev, V. A.; Sunyaev, R. A.; Skinner, G. K.
1997-07-01
We performed two series of observations of the X-ray source GX 339-4, a black-hole candidate, between 1989 and 1994 using the TTM instrument of the Roentgen Observatory. In March 1989, the source was in a soft state with a spectrum described by a multicolor accretion disk model (Shakura and Sunyaev 1973). In March 1994, a hard state with a power-law spectrum and a transition from the hard to the soft state was observed. The spectral states of the source show similarities to the spectra of other black-hole candidates. The presence of two states is considered as evidence that GX 339-4 belongs to this class of objects.
Lanzoni, B; Ferraro, F R; Miocchi, P; Valenti, E; Rood, R T
2007-01-01
We have used a combination of high resolution (HST ACS-HRC, ACS-WFC, and WFPC2) and wide-field (ESO-WFI) observations of the galactic globular cluster NGC 6388 to derive its center of gravity, projected density profile, and central surface brightness profile. While the overall projected profiles are well fit by a King model with intermediate concentration (c=1.8) and sizable core radius (rc=7"), a significant power law (with slope \\alpha=-0.2) deviation from a flat core behavior has been detected within the inner 1 arcsecond. These properties suggest the presence of a central intermediate mass black hole. The observed profiles are well reproduced by a multi-mass isotropic, spherical model including a black hole with a mass of ~5.7x10^3 Msol.
State-dependent bulk-boundary maps and black hole complementarity
Papadodimas, Kyriakos; Raju, Suvrat
2014-01-01
We provide a simple and explicit construction of local bulk operators that describe the interior of a black hole in the AdS/CFT correspondence. The existence of these operators is predicated on the assumption that the mapping of CFT operators to local bulk operators depends on the state of the CFT.
Analytical Study of Two-Mode Thermal Squeezed States and Black Holes
Venkataratnam, K. K.
2017-02-01
We study the two-mode thermal squeezed states formalism to examine the particle creation by black holes.We also study the entropy generation and derive an equation for Hawking temperature in terms of squeezed parameter and an associated temperature dependent parameters.
Remarks on the necessity and implications of state-dependence in the black hole interior
Papadodimas, Kyriakos; Raju, Suvrat
2016-01-01
We revisit the "state-dependence" of the map that we proposed recently between bulk operators in the interior of a large anti-de Sitter black hole and operators in the boundary CFT. By refining recent versions of the information paradox, we show that this feature is necessary for the CFT to successf
Average Density of States for Hermitian Wigner Matrices
Maltsev, Anna
2010-01-01
We consider ensembles of $N \\times N$ Hermitian Wigner matrices, whose entries are (up to the symmetry constraints) independent and identically distributed random variables. Assuming sufficient regularity for the probability density function of the entries, we show that the expectation of the density of states on {\\it arbitrarily} small intervals converges to the semicircle law, as $N$ tends to infinity.
Extracting Information about the Initial State from the Black Hole Radiation.
Lochan, Kinjalk; Padmanabhan, T
2016-02-05
The crux of the black hole information paradox is related to the fact that the complete information about the initial state of a quantum field in a collapsing spacetime is not available to future asymptotic observers, belying the expectations from a unitary quantum theory. We study the imprints of the initial quantum state contained in a specific class of distortions of the black hole radiation and identify the classes of in states that can be partially or fully reconstructed from the information contained within. Even for the general in state, we can uncover some specific information. These results suggest that a classical collapse scenario ignores this richness of information in the resulting spectrum and a consistent quantum treatment of the entire collapse process might allow us to retrieve much more information from the spectrum of the final radiation.
Spin squeezing and entanglement via hole-burning in atomic coherent states
Energy Technology Data Exchange (ETDEWEB)
Gerry, Christopher C. [Department of Physics and Astronomy, Lehman College, City University of New York, Bronx, NY 10468-1589 (United States)], E-mail: christopher.gerry@lehman.cuny.edu; Peart, Mark [Department of Physics and Astronomy, Lehman College, City University of New York, Bronx, NY 10468-1589 (United States)
2008-10-20
We study the generation of spin squeezing via the hole burning of selected Dicke states out of an atomic coherent state prepared for a collection of N two-level atoms or ions. The atoms or ions of the atomic coherent state are not entangled, but the removal of one or more Dicke states generates entanglement, and spin squeezing occurs for some ranges of the relevant parameters. Spin squeezing in a collection of two-level atoms or ions is of importance for precision spectroscopy.
Both electron and hole Dirac cone states in Ba(FeAs)2 confirmed by magnetoresistance.
Huynh, Khuong K; Tanabe, Yoichi; Tanigaki, Katsumi
2011-05-27
Quantum transport of Dirac cone states in the iron pnictide Ba(FeAs)(2) with a d-multiband system is studied by using single crystal samples. Transverse magnetoresistance develops linearly against the magnetic field at low temperatures. The transport phenomena are interpreted in terms of the zeroth Landau level by applying the theory predicted by Abrikosov. The results of the semiclassical analyses of a two carrier system in a low magnetic field limit show that both the electron and hole reside as the high mobility states. Our results show that pairs of electron and hole Dirac cone states must be taken into account for an accurate interpretation in iron pnictides, which is in contrast with previous studies.
Helical edge states and fractional quantum Hall effect in a graphene electron-hole bilayer.
Sanchez-Yamagishi, Javier D; Luo, Jason Y; Young, Andrea F; Hunt, Benjamin M; Watanabe, Kenji; Taniguchi, Takashi; Ashoori, Raymond C; Jarillo-Herrero, Pablo
2017-02-01
Helical 1D electronic systems are a promising route towards realizing circuits of topological quantum states that exhibit non-Abelian statistics. Here, we demonstrate a versatile platform to realize 1D systems made by combining quantum Hall (QH) edge states of opposite chiralities in a graphene electron-hole bilayer at moderate magnetic fields. Using this approach, we engineer helical 1D edge conductors where the counterpropagating modes are localized in separate electron and hole layers by a tunable electric field. These helical conductors exhibit strong non-local transport signals and suppressed backscattering due to the opposite spin polarizations of the counterpropagating modes. Unlike other approaches used for realizing helical states, the graphene electron-hole bilayer can be used to build new 1D systems incorporating fractional edge states. Indeed, we are able to tune the bilayer devices into a regime hosting fractional and integer edge states of opposite chiralities, paving the way towards 1D helical conductors with fractional quantum statistics.
Detecting entanglement of states by entries of their density matrices
Qi, Xiaofei
2010-01-01
For any bipartite systems, a universal entanglement witness of rank-4 for pure states is obtained and a class of finite rank entanglement witnesses is constructed. In addition, a method of detecting entanglement of a state only by entries of its density matrix is obtained.
Exact ensemble density-functional theory for excited states
Yang, Zeng-hui; Pribram-Jones, Aurora; Burke, Kieron; Needs, Richard J; Ullrich, Carsten A
2014-01-01
We construct exact Kohn-Sham potentials for the ensemble density-functional theory (EDFT) of excited states from the ground and excited states of helium. The exchange-correlation potential is compared with current approximations, which miss prominent features. The ensemble derivative discontinuity is tested, and the virial theorem is proven and illustrated.
On the density of states of disordered epitaxial graphene
Energy Technology Data Exchange (ETDEWEB)
Davydov, S. Yu., E-mail: Sergei-Davydov@mail.ru [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)
2015-05-15
The study is concerned with two types of disordered epitaxial graphene: (i) graphene with randomly located carbon vacancies and (ii) structurally amorphous graphene. The former type is considered in the coherent potential approximation, and for the latter type, a model of the density of states is proposed. The effects of two types of substrates, specifically, metal and semiconductor substrates are taken into account. The specific features of the density of states of epitaxial graphene at the Dirac point and the edges of the continuous spectrum are analyzed. It is shown that vacancies in epitaxial graphene formed on the metal substrate bring about logarithmic nulling of the density of states of graphene at the Dirac point and the edges of the continuous spectrum. If the Dirac point corresponds to the middle of the band gap of the semiconductor substrate, the linear trend of the density of states to zero in the vicinity of the Dirac point in defect-free graphene transforms into a logarithmic decrease in the presence of vacancies. In both cases, the graphene-substrate interaction is assumed to be weak (quasi-free graphene). In the study of amorphous epitaxial graphene, a simple model of free amorphous graphene is proposed as the initial model, in which account is taken of the nonzero density of states at the Dirac point, and then the interaction of the graphene sheet with the substrate is taken into consideration. It is shown that, near the Dirac point, the quadratic behavior of the density of states of free amorphous graphene transforms into a linear dependence for amorphous epitaxial graphene. In the study, the density of states of free graphene corresponds to the low-energy approximation of the electron spectrum.
Energy Technology Data Exchange (ETDEWEB)
Kapoor, Varun; Brics, Martins; Bauer, Dieter [Institut fuer Physik, Universitaet Rostock, 18051 Rostock (Germany)
2013-07-01
Autoionizing states are inaccessible to time-dependent density functional theory (TDDFT) using known, adiabatic Kohn-Sham (KS) potentials. We determine the exact KS potential for a numerically exactly solvable model Helium atom interacting with a laser field that is populating an autoionizing state. The exact single-particle density of the population in the autoionizing state corresponds to that of the energetically lowest quasi-stationary state in the exact KS potential. We describe how this exact potential controls the decay by a barrier whose height and width allows for the density to tunnel out and decay with the same rate as in the ab initio time-dependent Schroedinger calculation. However, devising a useful exchange-correlation potential that is capable of governing such a scenario in general and in more complex systems is hopeless. As an improvement over TDDFT, time-dependent reduced density matrix functional theory has been proposed. We are able to obtain for the above described autoionization process the exact time-dependent natural orbitals (i.e., the eigenfunctions of the exact, time-dependent one-body reduced density matrix) and study the potentials that appear in the equations of motion for the natural orbitals and the structure of the two-body density matrix expanded in them.
Quantum Entropy of Black Hole with Internal Global Monopole
Institute of Scientific and Technical Information of China (English)
HAN Yi-Wen; YANG Shu-Zheng; LIU Wen-Biao
2005-01-01
Using the generalized uncertainty relation, the new equation of state density is obtained, and then the entropy of black hole with an internal global monopole is discussed. The divergence that appears in black hole entropy calculation through original brick-wall model is overcome. The result of the direct proportion between black hole entropy and its event horizon area is drawn and given. The result shows that the black hole entropy must be the entropy of quantum state near the event horizon.
Giant Nernst effect in the incommensurate charge density wave state of P4W12O44
Kolincio, Kamil K.; Daou, Ramzy; Pérez, Olivier; Guérin, Laurent; Fertey, Pierre; Pautrat, Alain
2016-12-01
We report the study of Nernst effect in quasi-low-dimensional tungsten bronze P4W12O44 showing a sequence of Peierls instabilities. We demonstrate that both condensation of the electronic carriers in the charge density wave state and the existence of high-mobility electrons and holes originating from the small pockets remaining in the incompletely nested Fermi surface give rise to a Nernst effect of a magnitude similar to that observed in heavy fermion compounds.
Finite-size corrections to the density of states
Wörner, C. H.; Muñoz, E.
2012-09-01
The counting of states used in the well-known calculus of the density of states is revisited with emphasis on the error involved in the standard calculation. For pedagogical reasons, we restrict our treatment mainly to the two-dimensional case. This question is discussed in connection with the mathematical Gauss circle problem. It is shown that the typical error involved is negligible when the number of states tends to infinity.
A density functional equation of state for use in astrophysical phenomena
Olson, J. Pocahontas
2015-10-01
In this thesis, I present a new equation of state for use in simulating supernovae, black holes and neutron star mergers. It is the first such equation of state for astrophysical applications to use a density functional theory description for hadronic matter. The inclusion of thermal effects of matter enable nuclear Skyrme models, which have been highly tested and constrained at laboratory energy scales, to expand their domain to predictions of astronomical phenomena. Broadening the scope of these models can further confine parameter sets, using vastly different energy scales. The new equation of state, titled the Notre Dame-Livermore Equation of State (NDL EoS), allows for the creation of a pion condensate at high density and pair production of all known baryonic and mesonic states at high temperature. The description of matter also allows for the possibility of the formation of a net proton excess (Ye> 0:5). In addition to the density functional theory formulation for hadronic matter, the NDL EoS contains low and high density completions to better describe matter in these specific energy regimes. The low density description expands upon a Bowers and Wilson formulation, adding a transition through nuclear pasta phases, which are of particular importance in neutron star structure. These low density definitions have further been updated to include an improved treatment of the nuclear statistical equilibrium and the transition to heavy nuclei as the density approaches nuclear matter density. At high densities, matter is allowed to transition to a quark-gluon plasma (QGP) either as a first-order Gibbs transition, or a smooth crossover. Notre Dame-Livermore I identify predictions of the NDL EoS, contrasting them to existing equations of state and various Skyrme models of the NDL EoS. The observation of a heavy (two solar masses) neutron star restricts many descriptions of matter, and rules out several Skyrme parameter sets that had heretofore been entirely within the
The Z3 model with the density of states method
Mercado, Ydalia Delgado; Gattringer, Christof
2014-01-01
In this contribution we apply a new variant of the density of states method to the Z3 spin model at finite density. We use restricted expectation values evaluated with Monte Carlo simulations and study their dependence on a control parameter lambda. We show that a sequence of one-parameter fits to the Monte-Carlo data as a function of lambda is sufficient to completely determine the density of states. We expect that this method has smaller statistical errors than other approaches since all generated Monte Carlo data are used in the determination of the density. We compare results for magnetization and susceptibility to a reference simulation in the dual representation of the Z3 spin model and find good agreement for a wide range of parameters.
Metastable states of hydrogen: their geometric phases and flux densities
Gasenzer, T; Trappe, M -I
2011-01-01
We discuss the geometric phases and flux densities for the metastable states of hydrogen with principal quantum number n=2 being subjected to adiabatically varying external electric and magnetic fields. Convenient representations of the flux densities as complex integrals are derived. Both, parity conserving (PC) and parity violating (PV) flux densities and phases are identified. General expressions for the flux densities following from rotational invariance are derived. Specific cases of external fields are discussed. In a pure magnetic field the phases are given by the geometry of the path in magnetic field space. But for electric fields in presence of a constant magnetic field and for electric plus magnetic fields the geometric phases carry information on the atomic parameters, in particular, on the PV atomic interaction. We show that for our metastable states also the decay rates can be influenced by the geometric phases and we give a concrete example for this effect. Finally we emphasise that the general...
Markowitz, A
2005-01-01
We present a broadband power spectral density function (PSD) measured from extensive RXTE monitoring data of the low-luminosity AGN NGC 4258, which has an accurate, maser-determined black hole mass of 3.9+/-0.1 * 10^7 solar masses. We constrain the PSD break timescale to be greater than 4.5 d at >90% confidence, which appears to rule out the possibility that NGC 4258 is an analogue of black hole X-ray binaries (BHXRBs) in the high/soft state. In this sense, the PSD of NGC 4258 is different to those of some more-luminous Seyferts, which appear similar to the PSDs of high/soft state X-ray binaries. This result supports previous analogies between LLAGN and X-ray binaries in the low/hard state based on spectral energy distributions, indicating that the AGN/BHXRB analogy is valid across a broad range of accretion rates.
Kyutoku, Koutarou; Okawa, Hirotada; Shibata, Masaru; Taniguchi, Keisuke
2011-09-01
We study the merger of black hole-neutron star binaries with a variety of black hole spins aligned or antialigned with the orbital angular momentum, and with the mass ratio in the range MBH/MNS=2-5, where MBH and MNS are the mass of the black hole and neutron star, respectively. We model neutron-star matter by systematically parametrized piecewise polytropic equations of state. The initial condition is computed in the puncture framework adopting an isolated horizon framework to estimate the black hole spin and assuming an irrotational velocity field for the fluid inside the neutron star. Dynamical simulations are performed in full general relativity by an adaptive-mesh refinement code, SACRA. The treatment of hydrodynamic equations and estimation of the disk mass are improved. We find that the neutron star is tidally disrupted irrespective of the mass ratio when the black hole has a moderately large prograde spin, whereas only binaries with low mass ratios, MBH/MNS≲3, or small compactnesses of the neutron stars bring the tidal disruption when the black hole spin is zero or retrograde. The mass of the remnant disk is accordingly large as ≳0.1M⊙, which is required by central engines of short gamma-ray bursts, if the black hole spin is prograde. Information of the tidal disruption is reflected in a clear relation between the compactness of the neutron star and an appropriately defined “cutoff frequency” in the gravitational-wave spectrum, above which the spectrum damps exponentially. We find that the tidal disruption of the neutron star and excitation of the quasinormal mode of the remnant black hole occur in a compatible manner in high mass-ratio binaries with the prograde black hole spin. The correlation between the compactness and the cutoff frequency still holds for such cases. It is also suggested by extrapolation that the merger of an extremely spinning black hole and an irrotational neutron star binary does not lead to the formation of an overspinning
Particle-Hole Symmetry Breaking in the Pseudogap State of Bi2201
Energy Technology Data Exchange (ETDEWEB)
Hashimoto, M.; /SIMES, Stanford /Stanford U., Geballe Lab. /LBNL, ALS; He, R.-H.; /aff SIMES, Stanford /Stanford U., Geballe Lab.; Tanaka, K.; /aff SIMES, Stanford /Stanford U., Geballe Lab. /LBNL, ALS /Osaka U.; Testaud, J.P.; /SIMES, Stanford /Stanford U., Geballe Lab. /LBNL, ALS; Meevasana1, W.; Moore, R.G.; Lu, D.H.; /SIMES, Stanford /Stanford U., Geballe Lab.; Yao, H.; /SIMES, Stanford; Yoshida, Y.; Eisaki, H.; /AIST, Tsukuba; Devereaux, T.P.; /SIMES, Stanford /Stanford U., Geballe Lab.; Hussain, Z.; /LBNL, ALS; Shen, Z.-X.; /SIMES, Stanford /Stanford U., Geballe Lab.
2011-08-19
In conventional superconductors, a gap exists in the energy absorption spectrum only below the transition temperature (T{sub c}), corresponding to the energy price to pay for breaking a Cooper pair of electrons. In high-T{sub c} cuprate superconductors above T{sub c}, an energy gap called the pseudogap exists, and is controversially attributed either to pre-formed superconducting pairs, which would exhibit particle-hole symmetry, or to competing phases which would typically break it. Scanning tunnelling microscopy (STM) studies suggest that the pseudogap stems from lattice translational symmetry breaking and is associated with a different characteristic spectrum for adding or removing electrons (particle-hole asymmetry). However, no signature of either spatial or energy symmetry breaking of the pseudogap has previously been observed by angle-resolved photoemission spectroscopy (ARPES). Here we report ARPES data from Bi2201 which reveals both particle-hole symmetry breaking and dramatic spectral broadening indicative of spatial symmetry breaking without long range order, upon crossing through T* into the pseudogap state. This symmetry breaking is found in the dominant region of the momentum space for the pseudogap, around the so-called anti-node near the Brillouin zone boundary. Our finding supports the STM conclusion that the pseudogap state is a broken-symmetry state that is distinct from homogeneous superconductivity.
Density of states of Frenkel excitons in weakly disordered systems
Boukahil, Abdelkrim; Zettili, Nouredine
2002-04-01
We present the calculation of the density of states of Frenkel excitons in weakly disordered one , two , and three-dimensional systems. A random distribution of transition frequencies with variance s2 characterizes the disorder. The Coherent Potential Approximation (CPA) calculations show that the density of states (DOS) is very sensitive to any variations in the disorder parameter s. Our calculations are in good agreement with previous work based on the Monte Carlo simulation. One of us (AB) acknowldges the support of the University of Wisconsin--Whitewater for this work through a university research grant.
Continuity of Integrated Density of States - Independent Randomness
Indian Academy of Sciences (India)
M Krishna
2007-08-01
In this paper we discuss the continuity properties of the integrated density of states for random models based on that of the single site distribution. Our results are valid for models with independent randomness with arbitrary free parts. In particular in the case of the Anderson type models (with stationary, growing, decaying randomness) on the dimensional lattice, with or without periodic and almost periodic backgrounds, we show that if the single site distribution is uniformly -Hölder continuous, 0 < ≤ 1, then the density of states is also uniformly -Hölder continuous.
Joint Density of States Calculation Employing Wang-Landau Algorithm
Kalyan, M. Suman; Bharath, R.; Sastry, V. S. S.; Murthy, K. P. N.
2016-04-01
Joint density of states (JDoS), which depends both on energy and another variable like order parameter provides more information than the conventional density of states (DoS) which depend only on energy. Calculation of JDoS requires huge computational time. In this paper we employ two level method to calculate JDoS which requires relatively much less computational time. We demonstrate this method on a two dimensional Ising spin system, lattice spin model of double strand DNA (dsDNA) and Heisenberg ferromagnet.
Engineering the Photonic Density of States with metamaterials
Jacob*, Z; Naik, G V; Boltasseva, A; Shalaev, E Narimanov V M
2010-01-01
The photonic density of states (PDOS), like its' electronic coun- terpart, is one of the key physical quantities governing a variety of phenom- ena and hence PDOS manipulation is the route to new photonic devices. The PDOS is conventionally altered by exploiting the resonance within a device such as a microcavity or a bandgap structure like a photonic crystal. Here we show that nanostructured metamaterials with hyperbolic dispersion can dramatically enhance the photonic density of states paving the way for metamaterial based PDOS engineering.
Multiphase aluminum equations of state via density functional theory
Sjostrom, Travis; Crockett, Scott; Rudin, Sven
2016-10-01
We have performed density functional theory (DFT) based calculations for aluminum in extreme conditions of both pressure and temperature, up to five times compressed ambient density, and over 1 000 000 K in temperature. In order to cover such a domain, DFT methods including phonon calculations, quantum molecular dynamics, and orbital-free DFT are employed. The results are then used to construct a SESAME equation of state for the aluminum 1100 alloy, encompassing the fcc, hcp, and bcc solid phases as well as the liquid regime. We provide extensive comparison with experiment, and based on this we also provide a slightly modified equation of state for the aluminum 6061 alloy.
Quantum oscillations in the anomalous spin density wave state of FeAs
Campbell, Daniel J.; Eckberg, Chris; Wang, Kefeng; Wang, Limin; Hodovanets, Halyna; Graf, Dave; Parker, David; Paglione, Johnpierre
2017-08-01
Quantum oscillations in the binary antiferromagnetic metal FeAs are presented and compared to theoretical predictions for the electronic band structure in the anomalous spin density wave state of this material. Demonstrating a method for growing single crystals out of Bi flux, we utilize the highest quality FeAs to perform torque magnetometry experiments up to 35 T, using rotations of field angle in two planes to provide evidence for one electron and one hole band in the magnetically ordered state. The resulting picture agrees with previous experimental evidence for multiple carriers at low temperatures, but the exact Fermi surface shape differs from predictions, suggesting that correlations play a role in deviation from ab initio theory and cause up to a fourfold enhancement in the effective carrier mass.
Milagro Limits on the Rate-Density of Primordial Black Holes
Ukwatta, T U; Linnemann, J T; Tollefson, K; Vasileiou, V; Sinnis, G; MacGibbon, J H
2013-01-01
Primordial Black Holes (PBHs) created early in the universe are dark matter candidates. One method of detecting these PBHs is through their Hawking radiation. PBHs created with an initial mass of 5.0 x 10^14 g should be evaporating today with bursts of high-energy particles, including gamma radiation in the GeV - TeV energy range. The Milagro high energy observatory, which operated from 2000 to 2008, is sensitive to the high end of the PBH evaporation gamma ray spectrum. Due to its large field-of-view, more than 90% duty cycle and sensitivity up to 100 TeV gamma rays, the Milagro observatory is ideally suited for the direct search of PBH bursts. Based on a search in Milagro data, we report PBH upper limits according to the standard model.
Fast electronic resistance switching involving hidden charge density wave states
Vaskivskyi, I.; Mihailovic, I. A.; Brazovskii, S.; Gospodaric, J.; Mertelj, T.; Svetin, D.; Sutar, P.; Mihailovic, D.
2016-05-01
The functionality of computer memory elements is currently based on multi-stability, driven either by locally manipulating the density of electrons in transistors or by switching magnetic or ferroelectric order. Another possibility is switching between metallic and insulating phases by the motion of ions, but their speed is limited by slow nucleation and inhomogeneous percolative growth. Here we demonstrate fast resistance switching in a charge density wave system caused by pulsed current injection. As a charge pulse travels through the material, it converts a commensurately ordered polaronic Mott insulating state in 1T-TaS2 to a metastable electronic state with textured domain walls, accompanied with a conversion of polarons to band states, and concurrent rapid switching from an insulator to a metal. The large resistance change, high switching speed (30 ps) and ultralow energy per bit opens the way to new concepts in non-volatile memory devices manipulating all-electronic states.
Exact sign structure of the t–J chain and the single hole ground state
Directory of Open Access Journals (Sweden)
Zheng Zhu
2016-02-01
Full Text Available Injecting a single hole into a one-dimensional Heisenberg spin chain is probably the simplest case of doping a Mott insulator. The motion of such a single hole will generally induce a many-body phase shift, which can be identified by an exact sign structure of the model known as the phase string. We show that the sign structure is nontrivial even in this simplest problem, which is responsible for the essential properties of Mott physics. We find that the characteristic momentum structure, the Luttinger liquid behavior, and the quantum phase interference of the hole under a periodic boundary condition can all be attributed to it. We use the density matrix renormalization group (DMRG numerical simulation to make a comparative study of the t–J chain and a model in which the sign structure is switched off. We further show that the key DMRG results can be reproduced by a variational wave function with incorporating the correct sign structure. Physical implications of the sign structure for doped Mott insulators in general are also discussed.
Extracting information about the initial state from the black hole radiation
Lochan, Kinjalk
2015-01-01
The crux of the black hole information paradox is related to the fact that the complete information about the initial state of a quantum field in a collapsing spacetime is not available to future asymptotic observers, belying the expectations from a unitary quantum theory. We study the imprints of the initial quantum state, contained in the distortions of the black hole radiation from the thermal spectrum, which can be detected by the asymptotic observers. We identify the class of in-states which can be fully reconstructed from the information contained in the distortions at the semiclassical level. Even for the general in-state, we can uncover a specific amount of information about the initial state. For a large class of initial states, some specific observables defined in the initial Hilbert space are completely determined from the resulting final spectrum. These results suggest that a \\textit{classical} collapse scenario ignores this richness of information in the resulting spectrum and a consistent quantu...
Black hole entropy without brick walls
Xiang, Li
2002-01-01
The properties of the thermal radiation are discussed by using the new equation of state density motivated by the generalized uncertainty relation in the quantum gravity. There is no burst at the last stage of the emission of a Schwarzshild black hole. When the new equation of state density is utilized to investigate the entropy of a scalar field outside the horizon of a static black hole, the divergence appearing in the brick wall model is removed, without any cutoff. The entropy proportiona...
State-space geometry, non-extremal black holes and Kaluza-Klein monopoles
Bellucci, Stefano
2012-01-01
We examine the statistical nature of the charged anticharged non-extremal black holes in string theory. From the perspective of the intrinsic Riemannian Geometry, the first principle of the statistical mechanics shows that the stability properties of general nonextremal nonlarge charged black brane solutions are divulged from the positivity of the corresponding principle minors of the space-state metric tensor. Under the addition of the Kaluza-Klein monopoles, a novel aspect of the Gaussian fluctuations demonstrates that the canonical fluctuations can be ascertained without any approximation. We offer the state-space geometric implication for the most general non-extremal black brane configurations in string theory.
The X-ray Power Spectral Density Function and Black Hole Mass Estimate for the Seyfert AGN IC 4329a
Markowitz, A
2009-01-01
We present the X-ray broadband power spectral density function (PSD) of the X-ray-luminous Seyfert IC 4329a, constructed from light curves obtained via Rossi X-ray Timing Explorer monitoring and an XMM-Newton observation. Modeling the 3-10 keV PSD using a broken power-law PSD shape, a break in power-law slope is significantly detected at a temporal frequency of 2.5(+2.5,-1.7) * 10^-6 Hz, which corresponds to a PSD break time scale T_b of 4.6(+10.1,-2.3) days. Using the relation between T_b, black hole mass M_BH, and bolometric luminosity as quantified by McHardy and coworkers, we infer a black hole mass estimate of M_BH = 1.3(+1.0,-0.3) * 10^8 solar masses and an accretion rate relative to Eddington of 0.21(+0.06,-0.10) for this source. Our estimate of M_BH is consistent with other estimates, including that derived by the relation between M_BH and stellar velocity dispersion. We also present PSDs for the 10-20 and 20-40 keV bands; they lack sufficient temporal frequency coverage to reveal a significant break,...
Partovi-Azar, Pouya; Kaghazchi, Payam
2017-04-15
We report on real-time time-dependent density functional theory calculations on direction-dependent electron and hole transfer processes in molecular systems. As a model system, we focus on α-sulfur. It is shown that time scale of the electron transfer process from a negatively charged S8 molecule to a neighboring neutral monomer is comparable to that of a strong infrared-active molecular vibrations of the dimer with one negatively charged monomer. This results in a strong coupling between the electrons and the nuclei motion which eventually leads to S8 ring opening before the electron transfer process is completed. The open-ring structure is found to be stable. The similar infrared-active peak in the case of hole transfer, however, is shown to be very weak and hence no significant scattering by the nuclei is possible. The presented approach to study the charge transfer processes in sulfur has direct applications in the increasingly growing research field of charge transport in molecular systems. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.
The transition to the metallic state in low density hydrogen.
McMinis, Jeremy; Morales, Miguel A; Ceperley, David M; Kim, Jeongnim
2015-11-21
Solid atomic hydrogen is one of the simplest systems to undergo a metal-insulator transition. Near the transition, the electronic degrees of freedom become strongly correlated and their description provides a difficult challenge for theoretical methods. As a result, the order and density of the phase transition are still subject to debate. In this work, we use diffusion quantum Monte Carlo to benchmark the transition between paramagnetic and anti-ferromagnetic body centered cubic atomic hydrogen in its ground state. We locate the density of the transition by computing the equation of state for these two phases and identify the phase transition order by computing the band gap near the phase transition. These benchmark results show that the phase transition is continuous and occurs at a Wigner-Seitz radius of rs = 2.27(3) a0. We compare our results to previously reported density functional theory, Hedin's GW approximation, and dynamical mean field theory results.
Black holes as self-sustained quantum states and Hawking radiation
Casadio, Roberto; Giugno, Andrea; Micu, Octavian; Orlandi, Alessio
2014-10-01
We employ the recently proposed formalism of the "horizon wave function" to investigate the emergence of a horizon in models of black holes as Bose-Einstein condensates of gravitons. We start from the Klein-Gordon equation for a massless scalar (toy graviton) field coupled to a static matter current. The (spherically symmetric) classical field reproduces the Newtonian potential generated by the matter source, and the corresponding quantum state is given by a coherent superposition of scalar modes with continuous occupation number. Assuming an attractive self-interaction that allows for bound states, one finds that (approximately) only one mode is allowed, and the system can be confined in a region the size of the Schwarzschild radius. This radius is then shown to correspond to a proper horizon, by means of the horizon wave function of the quantum system, with an uncertainty in size naturally related to the expected typical energy of Hawking modes. In particular, this uncertainty decreases for larger black hole mass (with a larger number of light scalar quanta), in agreement with semiclassical expectations, a result which does not hold for a single very massive particle. We finally speculate that a phase transition should occur during the gravitational collapse of a star (ideally represented by a static matter current and Newtonian potential) that leads to a black hole (again ideally represented by the condensate of toy gravitons), and suggest an effective order parameter that could be used to investigate this transition.
Kvaal, Simen; Helgaker, Trygve
2015-11-14
The relationship between the densities of ground-state wave functions (i.e., the minimizers of the Rayleigh-Ritz variation principle) and the ground-state densities in density-functional theory (i.e., the minimizers of the Hohenberg-Kohn variation principle) is studied within the framework of convex conjugation, in a generic setting covering molecular systems, solid-state systems, and more. Having introduced admissible density functionals as functionals that produce the exact ground-state energy for a given external potential by minimizing over densities in the Hohenberg-Kohn variation principle, necessary and sufficient conditions on such functionals are established to ensure that the Rayleigh-Ritz ground-state densities and the Hohenberg-Kohn ground-state densities are identical. We apply the results to molecular systems in the Born-Oppenheimer approximation. For any given potential v ∈ L(3/2)(ℝ(3)) + L(∞)(ℝ(3)), we establish a one-to-one correspondence between the mixed ground-state densities of the Rayleigh-Ritz variation principle and the mixed ground-state densities of the Hohenberg-Kohn variation principle when the Lieb density-matrix constrained-search universal density functional is taken as the admissible functional. A similar one-to-one correspondence is established between the pure ground-state densities of the Rayleigh-Ritz variation principle and the pure ground-state densities obtained using the Hohenberg-Kohn variation principle with the Levy-Lieb pure-state constrained-search functional. In other words, all physical ground-state densities (pure or mixed) are recovered with these functionals and no false densities (i.e., minimizing densities that are not physical) exist. The importance of topology (i.e., choice of Banach space of densities and potentials) is emphasized and illustrated. The relevance of these results for current-density-functional theory is examined.
The local density of optical states of a metasurface
Lunnemann, P.; Koenderink, A.F.
2016-01-01
While metamaterials are often desirable for near-field functions, such as perfect lensing, or cloaking, they are often quantified by their response to plane waves from the far field. Here, we present a theoretical analysis of the local density of states near lattices of discrete magnetic scatterers,
Anharmonic densities of states: A general dynamics-based solution
Jellinek, Julius; Aleinikava, Darya
2016-06-01
Density of states is a fundamental physical characteristic that lies at the foundation of statistical mechanics and theoretical constructs that derive from them (e.g., kinetic rate theories, phase diagrams, and others). Even though most real physical systems are anharmonic, the vibrational density of states is customarily treated within the harmonic approximation, or with some partial, often limited, account for anharmonicity. The reason for this is that the problem of anharmonic densities of states stubbornly resisted a general and exact, yet convenient and straightforward in applications, solution. Here we formulate such a solution within both classical and quantum mechanics. It is based on actual dynamical behavior of systems as a function of energy and as observed, or monitored, on a chosen time scale, short or long. As a consequence, the resulting anharmonic densities of states are fully dynamically informed and, in general, time-dependent. As such, they lay the ground for formulation of new statistical mechanical frameworks that incorporate time and are ergodic, by construction, with respect to actual dynamical behavior of systems.
Density of conformon states in a disordered polymeric crystal
Klinskikh, A. F.
1999-03-01
Following Volkenstein's idea the density of conformon states (rho) (E) is investigated. Using the path-integral method in conditions of the strong conformational disorder the numerical account (rho) (E) is carried out. The results of account (rho) (E) under the new formula are discussed.
The QCD equation of state at nonzero densities lattice result
Fodor, Z; Szabó, K K
2003-01-01
In this letter we give the equation of state of QCD at finite temperatures and densities. The recently proposed overlap improving multi-parameter reweighting technique is used to determine observables at nonvanishing chemical potentials. Our results are obtained by studying n_f=2+1 dynamical staggered quarks with semi-realistic masses on N_t=4 lattices.
A magnetic model for low/hard state of black hole binaries
Ye, Yong-Chun; Huang, Chang-Yin; Cao, Xiao-Feng
2015-01-01
A magnetic model for low/hard state (LHS) of black hole X-ray binaries (BHXBs),H1743-322 and GX 339-4, is proposed based on the transportation of magnetic field from a companion into an accretion disk around a black hole (BH). This model consists of a truncated thin disk with an inner advection-dominated accretion flow (ADAF). The spectral profiles of the sources are fitted in agreement with the data observed at four different dates corresponding to the rising phase of the LHS. In addition, the association of the LHS with quasi-steady jet is modelled based on transportation of magnetic field, where the Blandford-Znajek (BZ) and Blandford-Payne (BP) processes are invoked to drive the jets from BH and inner ADAF. It turns out that the steep radio/X-ray correlations observed in H1743-322 and GX 339-4 can be interpreted based on our model.
Relativistic Accretion Disk Models of High State Black Hole X-ray Binary Spectra
Davis, S W; Hubeny, I; Turner, N J; Davis, Shane W.; Blaes, Omer M.; Hubeny, Ivan; Turner, Neal J.
2004-01-01
We present calculations of non-LTE, relativistic accretion disk models applicable to the high/soft state of black hole X-ray binaries. We include the effects of thermal Comptonization and bound-free and free-free opacities of all abundant ion species. We present spectra calculated for a variety of accretion rates, black hole spin parameters, disk inclinations, and stress prescriptions. We also consider nonzero inner torques on the disk, and explore different vertical dissipation profiles, including some which are motivated by recent radiation MHD simulations of magnetorotational turbulence. Bound-free metal opacity generally produces significantly less spectral hardening than previous models which only considered Compton scattering and free-free opacity. It also tends to keep the effective photosphere near the surface, resulting in spectra which are remarkably independent of the stress prescription and vertical dissipation profile, provided little dissipation occurs above the effective photosphere. We provide...
Outbursts and State Transitions in Black Hole Candidates observed by MAXI
Negoro, H.; Maxi Team
2010-12-01
MAXI continuously observes several black hole candidates in our Galaxy and LMC. MAXI already detected various state transitions in Cyg X-1, GX 339-4, Swift J1752.5-127, and black hole transients, H 1743-332, 4U 1630, XTE J1752-223, and MAXI J1659-125. From these observations, we try to clarify what happens during the transitions, and what triggers the transitions. In any case, fast alerts just before the transitions and soon after the outbursts are crucial to detect, for instance, radio and high energy gamma-ray jets or emission. We also present some successful examples of alerts from our MAXI transient alert system.
Spin-state polarons in lightly-hole-doped LaCoO3.
Podlesnyak, A; Russina, M; Furrer, A; Alfonsov, A; Vavilova, E; Kataev, V; Büchner, B; Strässle, Th; Pomjakushina, E; Conder, K; Khomskii, D I
2008-12-12
Inelastic neutron scattering (INS), electron spin resonance (ESR), and nuclear magnetic resonance (NMR) measurements were employed to establish the origin of the strong magnetic signal in lightly-hole-doped La1-xSrxCoO3, x approximately 0.002. Both INS and ESR low temperature spectra show intense excitations with large effective g factors approximately 10-18. NMR data indicate the creation of extended magnetic clusters. From the Q dependence of the INS magnetic intensity, we conclude that the observed anomalies are caused by the formation of octahedrally shaped spin-state polarons comprising seven Co ions. The present INS, ESR, and NMR data give evidence for two regimes in the lightly-hole-doped samples: (i) T35 K dominated by thermally activated magnetic Co3+ ions.
Spin-state polarons in lightly hole-doped LaCoO3
Energy Technology Data Exchange (ETDEWEB)
Podlesnyak, Andrey A [ORNL; Russina, Margarita [Hahn-Meitner Institut, Berlin, Germany; Furrer, Albert [Laboratory for Neutron Scattering ETHZ & PSI; Alfonsov, Aleksei [IFW Dresden; Vavilova, Eugenia [IFW Dresden; Kataev, Vladislav [IFW Dresden; Buechner, Bernd [IFW Dresden; Straessle, Thierry [Laboratory for Neutron Scattering ETHZ & PSI; Pomjakushina, Ekaterina [Paul Scherrer Institut, Villigen, Switzerland; Conder, Kazimierz [Paul Scherrer Institut, Villigen, Switzerland; Khomskii, Daniel [Universitat zu Koln, Koln, Germany
2008-01-01
Inelastic neutron scattering (INS), electron spin resonance (ESR), and nuclear magnetic resonance (NMR) measurements were employed to establish the origin of the strong magnetic signal in lightly-hole-doped La{sub 1-x}Sr{sub x}CoO{sub 3}, x{approx}0.002. Both INS and ESR low temperature spectra show intense excitations with large effective g factors {approx}10-18. NMR data indicate the creation of extended magnetic clusters. From the Q dependence of the INS magnetic intensity, we conclude that the observed anomalies are caused by the formation of octahedrally shaped spin-state polarons comprising seven Co ions. The present INS, ESR, and NMR data give evidence for two regimes in the lightly-hole-doped samples: (i) T < 35 K dominated by spin polarons; (ii) T > 35 K dominated by thermally activated magnetic Co{sup 3+} ions.
Reis, R C; Fabian, A C; Cackett, E M; Maitra, D; Reynolds, C S; Rupen, M; Steeghs, D T H; Wijnands, R
2010-01-01
The Galactic Black hole candidate XTE J1752-223 was observed during the decay of its 2009 outburst with the Suzaku and XMM-Newton observatories. The observed spectra are consistent with the source being in the ''intermediate`` and ''low-hard state`` respectively. The presence of a strong, relativistic iron emission line is clearly detected in both observations and the line profiles are found to be remarkably consistent and robust to a variety of continuum models. This strongly points to the compact object in \\j\\ being a stellar-mass black hole accretor and not a neutron star. Physically-motivated and self-consistent reflection models for the Fe-\\ka\\ emission-line profile and disk reflection spectrum rule out either a non-rotating, Schwarzchild black hole or a maximally rotating, Kerr black hole at greater than 3sigma level of confidence. Using a fully relativistic line function in which the black hole spin parameter is a variable, we have formally constrained the spin parameter to be $0.52\\pm0.11 (1\\sigma)$. ...
Black hole formation and growth with non-Gaussian primordial density perturbations
Habouzit, Mélanie; Latif, Muhammad; Nishimichi, Takahiro; Peirani, Sébastien; Dubois, Yohan; Mamon, Gary A; Silk, Joseph; Chevallard, Jacopo
2015-01-01
Quasars powered by massive black holes (BHs) with mass estimates above a billion solar masses have been identified at redshift 6 and beyond. The existence of such BHs requires almost continuous growth at the Eddington limit for their whole lifetime, of order of one billion years. In this paper, we explore the possibility that positively skewed scale-dependent non-Gaussian primordial fluctuations may ease the assembly of massive BHs. In particular, they produce more low-mass halos at high redshift, thus altering the production of metals and ultra-violet flux, believed to be important factors in BH formation. Additionally, a higher number of progenitors and of nearly equal-mass halo mergers would boost the mass increase provided by BH-BH mergers and merger-driven accretion. We use a set of two cosmological simulations, with either Gaussian or scale-dependent non-Gaussian primordial fluctuations to perform a proof-of-concept experiment to estimate how BH formation and growth are altered. We estimate the BH numbe...
Suppression of Superfluid Density and the Pseudogap State in the Cuprates by Impurities.
Erdenemunkh, Unurbat; Koopman, Brian; Fu, Ling; Chatterjee, Kamalesh; Wise, W D; Gu, G D; Hudson, E W; Boyer, Michael C
2016-12-16
We use scanning tunneling microscopy (STM) to study magnetic Fe impurities intentionally doped into the high-temperature superconductor Bi_{2}Sr_{2}CaCu_{2}O_{8+δ}. Our spectroscopic measurements reveal that Fe impurities introduce low-lying resonances in the density of states at Ω_{1}≈4 meV and Ω_{2}≈15 meV, allowing us to determine that, despite having a large magnetic moment, potential scattering of quasiparticles by Fe impurities dominates magnetic scattering. In addition, using high-resolution spatial characterizations of the local density of states near and away from Fe impurities, we detail the spatial extent of impurity-affected regions as well as provide a local view of impurity-induced effects on the superconducting and pseudogap states. Our studies of Fe impurities, when combined with a reinterpretation of earlier STM work in the context of a two-gap scenario, allow us to present a unified view of the atomic-scale effects of elemental impurities on the pseudogap and superconducting states in hole-doped cuprates; this may help resolve a previously assumed dichotomy between the effects of magnetic and nonmagnetic impurities in these materials.
Proton-hole states in the N=30 neutron-rich {sup 49}K isotope.
Energy Technology Data Exchange (ETDEWEB)
Broda, R.; Wrzesinski, J.; Gadea, A.; Marginean, N.; Fornal, B.; Carpenter, M. P.; Janssens, R. V. F.; Zhu, S. (Physics); (Niewodniczanski Inst. of Nuclear Physics); (INFN Lab. Nazionali di Legnaro); (Dipartimento di Fisica dell' Universita); (INFN-Sezione di Napoli); (Michigan State Univ.); (National Inst. for Physics and Nuclear Engineering); (Ruder Boskovic Inst.); (CSIC-Univ. de Valencia); (Univ. of West of Scotland)
2010-09-22
Excited states in the N=30 neutron-rich isotope {sup 49}K have been studied using multinucleon transfer reactions with thin targets and the PRISMA-CLARA spectrometer combined with thick-target {gamma}-coincidence data from Gammasphere. The d{sub 3/2} proton-hole state is located 92 keV above the s{sub 1/2} ground state, and the proton-particle f{sub 7/2} state is suggested at 2104 keV. Three other levels are established as involving the coupling to 2{sup +} of two neutrons above the N=28 shell. The measured or estimated lifetimes served to reinforce the interpretation of the observed level structure, which is found to be in satisfactory agreement with shell-model calculations.
High-concurrence steady-state entanglement of two hole spins in a quantum dot molecular
Yang, Song; Li, ChuanFeng; Zou, XuBo; Guo, GuangCan
2009-01-01
Entanglement, a non-trivial phenomena manifested in composite quantum system, can be served as a new type of physical resource in the emerging technology of quantum information and quantum computation. However, a quantum entanglement is fragile to the environmental-induced decoherence. Here, we present a novel way to prepare a high-concurrence steady-state entanglement of two hole spins in a quantum dot molecular via optical pumping of trion levels. In this scheme, the spontaneous dispassion is used to induce and stabilize the entanglement with rapid rate. It is firstly shown that under certain conditions, two-qubit singlet state can be generated without requiring the state initialization. Then we study the effect of acoustic phonons and electron tunnelings on the scheme, and show that the concurrence of entangled state can be over 0.95 at temperature $T = 1 $K.
Spectral hardening as a viable alternative to disc truncation in black hole state transitions
Salvesen, Greg; Reis, Rubens C; Begelman, Mitchell C
2013-01-01
Constraining the accretion flow geometry of black hole binaries in outburst is complicated by the inability of simplified multi-colour disc models to distinguish between changes in the inner disc radius and alterations to the emergent spectrum, parameterised by the phenomenological colour correction factor, f_col. We analyse Rossi X-ray Timing Explorer observations of the low mass Galactic black hole X-ray binary, GX 339-4, taken over seven epochs when the source was experiencing a state transition. The accretion disc component is isolated using a pipeline resulting in robust detections for disc luminosities, 0.001 < L_disc / L_Edd < 0.5. Assuming that the inner disc remains situated at the innermost stable circular orbit over the course of a state transition, we measure the relative degree of change in f_col required to explain the spectral evolution of the disc component. A variable f_col that increases by a factor of ~ 2.0 - 3.5 as the source transitions from the high/soft state to the low/hard state...
Hot accretion flow with radiative cooling: state transitions in black hole X-ray binaries
Wu, Mao-Chun; Xie, Fu-Guo; Yuan, Ye-Fei; Gan, Zhaoming
2016-06-01
We investigate state transitions in black hole X-ray binaries through different parameters by using two-dimensional axisymmetric hydrodynamical simulation method. For radiative cooling in hot accretion flow, we take into account the bremsstrahlung, synchrotron and synchrotron self-Comptonization self-consistently in the dynamics. Our main result is that the state transitions occur when the accretion rate reaches a critical value dot{M} ˜ 3α dot{M}_Edd, above which cold and dense clumpy/filamentary structures are formed, embedded within the hot gas. We argued this mode likely corresponds to the proposed two-phase accretion model, which may be responsible for the intermediate state of black hole X-ray binaries. When the accretion rate becomes sufficiently high, the clumpy/filamentary structures gradually merge and settle down on to the mid-plane. Eventually the accretion geometry transforms to a disc-corona configuration. In summary, our results are consistent with the truncated accretion scenario for the state transition.
Yu, Shaocai; Alapaty, Kiran; Mathur, Rohit; Pleim, Jonathan; Zhang, Yuanhang; Nolte, Chris; Eder, Brian; Foley, Kristen; Nagashima, Tatsuya
2014-11-06
Aerosols can influence the climate indirectly by acting as cloud condensation nuclei and/or ice nuclei, thereby modifying cloud optical properties. In contrast to the widespread global warming, the central and south central United States display a noteworthy overall cooling trend during the 20(th) century, with an especially striking cooling trend in summertime daily maximum temperature (Tmax) (termed the U.S. "warming hole"). Here we used observations of temperature, shortwave cloud forcing (SWCF), longwave cloud forcing (LWCF), aerosol optical depth and precipitable water vapor as well as global coupled climate models to explore the attribution of the "warming hole". We find that the observed cooling trend in summer Tmax can be attributed mainly to SWCF due to aerosols with offset from the greenhouse effect of precipitable water vapor. A global coupled climate model reveals that the observed "warming hole" can be produced only when the aerosol fields are simulated with a reasonable degree of accuracy as this is necessary for accurate simulation of SWCF over the region. These results provide compelling evidence of the role of the aerosol indirect effect in cooling regional climate on the Earth. Our results reaffirm that LWCF can warm both winter Tmax and Tmin.
Form the density-of-states method to finite density quantum field theory
Langfeld, Kurt
2016-01-01
During the last 40 years, Monte Carlo calculations based upon Importance Sampling have matured into the most widely employed method for determinig first principle results in QCD. Nevertheless, Importance Sampling leads to spectacular failures in situations in which certain rare configurations play a non-secondary role as it is the case for Yang-Mills theories near a first order phase transition or quantum field theories at finite matter density when studied with the re-weighting method. The density-of-states method in its LLR formulation has the potential to solve such overlap or sign problems by means of an exponential error suppression. We here introduce the LLR approach and its generalisation to complex action systems. Applications include U(1), SU(2) and SU(3) gauge theories as well as the Z3 spin model at finite densities and heavy-dense QCD.
Schindler, Jan-Torge; Duschl, Wolfgang J
2016-01-01
At redshifts beyond $z{\\sim}1$ measuring the black hole galaxy relations proves to be a difficult task. The bright light of the AGN aggravates deconvolution of black hole and galaxy properties. On the other hand high redshift data on these relations is vital to understand in what ways galaxies and black holes co-evolve and in what ways they don't. In this work we use black hole (BHMDs) and stellar mass densities (SMDs) to constrain the possible co-evolution of black holes with their host galaxies since $z{\\sim}5$. The BHMDs are calculated from quasar luminosity functions (QLF) using the Soltan argument, while we use integrals over stellar mass functions (SMFs) or the star formation rate density to obtain values for the stellar mass density. We find that both quantities grow in lock-step below redshifts of $z{\\sim}3$ with a non-evolving BHMD to SMD ratio. A fit to the data assuming a power law relation between the BHMD and the SMD yields exponents around unity ($1.0{-}1.5$). Up to $z{\\sim}5$ the BHMD to SMD ra...
Steady-State Density Functional Theory for Finite Bias Conductances.
Stefanucci, G; Kurth, S
2015-12-09
In the framework of density functional theory, a formalism to describe electronic transport in the steady state is proposed which uses the density on the junction and the steady current as basic variables. We prove that, in a finite window around zero bias, there is a one-to-one map between the basic variables and both local potential on as well as bias across the junction. The resulting Kohn-Sham system features two exchange-correlation (xc) potentials, a local xc potential, and an xc contribution to the bias. For weakly coupled junctions the xc potentials exhibit steps in the density-current plane which are shown to be crucial to describe the Coulomb blockade diamonds. At small currents these steps emerge as the equilibrium xc discontinuity bifurcates. The formalism is applied to a model benzene junction, finding perfect agreement with the orthodox theory of Coulomb blockade.
Density of States Simulations of Various Glass Formers
Ghosh, Jayeeta; Faller, Roland
2008-02-01
The behavior of glassy systems in bulk and especially in confined geometries has received considerable attention over the last decades because of the technological importance and inherent complexity of the systems near or below the transition temperature. Confined glasses have been studied using different theoretical and experimental techniques which helped shape our understanding; but still huge gaps remain. In this work we are using the Wang-Landau Monte Carlo approach to study different model glasses. General Monte Carlo fails to sample all relevant regions of phase space; the application of this method gives us the opportunity to directly estimate the density of states and consequently any other thermodynamic properties. We can calculate properties in different ensembles using the same simulation runs. This random walk algorithm is designed to visit all energy states with equal probability to produce a flat histogram. We can estimate the density of states on the fly whenever any energy state is visited. We perform multiple simulations in overlapping energy regions and finally join them after proper scaling to obtain the overall density of states; the global density of states of the glass former is then known to within a constant. We apply this technique to a model binary Lennard Jones glass which is a well tested model, as well as for the first time to a realistic glass forming system, the small organic glass former Ortho-terphenyl (OTP). For OTP we start from a united atom model and derive systematically a coarse-grained representation by replacing each phenyl ring with one interaction site. We apply the Iterative Boltzmann Inversion for this purpose. This method relies on the structure of the atomistic model, mainly the radial distribution function (RDF). One needs to Boltzmann invert the atomistic RDF to obtain an initial guess for the non-bonded potential. Then using this potential for the preliminary coarse grained run gives a first set of RDFs to compare
Electrostatic density measurements in green-state PM parts
Leuenberger, Georg H. W.
The goal of this research is to show the feasibility of detecting density variations in greenstate powder metallurgy (P/M) compacts from surface voltage measurements. By monitoring a steady electric current flow through the sample and recording the voltages over the surface, valuable information is gathered leading to the prediction of the structural health of the compacts. Unlike prior research that concentrated on the detection of surface-breaking and subsurface defects, the results presented in this thesis target the density prediction throughout the volume of the sample. The detection of density variations is achieved by establishing a correlation between the conductivity and their respective density. The data obtained from the surface measurements is used as part of an inversion algorithm, calculating the conductivity distribution, and subsequently the density within the compact. In a first step, the relationship between conductivity and density of green-state P/M compacts was investigated. Tests were conducted for a number of parts of various powder mixtures. In all cases a clear correlation between conductivity and density could be established, indicating that measurements of electric conductivity could indeed be exploited in an effort to render valid information about the density of the sample under test. We found a linear correlation for nonlubricated parts and a non-linear behavior for lubricated samples. Specifically, it was found that the conductivity increases with increasing density only up to a maximum value obtained at approximately 6.9g/cm 3. Interestingly, any additional density increase leads to a reduction of the conductivity. This behavior was confirmed to be inherent in all powder mixtures with lubricants. The thesis research is able to provide a physical model and a mathematical formulation describing this counter-intuitive phenomenon. A finite element solver in conjunction with an inversion algorithm was then implemented to study arbitrarily
Determination of the density of states of. cap alpha. -Si:H using the field effect
Energy Technology Data Exchange (ETDEWEB)
Goodman, N B; Fritzsche, H; Ozaki, H
1979-01-01
A new iterative computer method has been devised for obtaining N(E), the density of gap states, from field effect data without using simplifying approximations. Analysis shows that equally good fits to the data can be obtained over a range of values of the ratio of electron and hole contributions to the conductivity in the bulk and of the field voltage needed to obtain flat bands. The present experimental accuracy is not sufficient to discern detailed structure in N(E). The validity of assuming a parallel shift of the mobility edge with the potential near the interface is being questioned. Field effect data on undoped glow-discharge ..cap alpha..-Si:H subjected to the Staebler-Wronski cycle of illumination and heat treatment are presented and analyzed.
Accretion onto some well-known regular black holes
Energy Technology Data Exchange (ETDEWEB)
Jawad, Abdul; Shahzad, M.U. [COMSATS Institute of Information Technology, Department of Mathematics, Lahore (Pakistan)
2016-03-15
In this work, we discuss the accretion onto static spherically symmetric regular black holes for specific choices of the equation of state parameter. The underlying regular black holes are charged regular black holes using the Fermi-Dirac distribution, logistic distribution, nonlinear electrodynamics, respectively, and Kehagias-Sftesos asymptotically flat regular black holes. We obtain the critical radius, critical speed, and squared sound speed during the accretion process near the regular black holes. We also study the behavior of radial velocity, energy density, and the rate of change of the mass for each of the regular black holes. (orig.)
Accretion onto Some Well-Known Regular Black Holes
Jawad, Abdul
2016-01-01
In this work, we discuss the accretion onto static spherical symmetric regular black holes for specific choices of equation of state parameter. The underlying regular black holes are charged regular black hole using Fermi-Dirac Distribution, logistic distribution, nonlinear electrodynamics, respectively and Kehagias-Sftesos asymptotically flat regular black hole. We obtain the critical radius, critical speed and squared sound speed during the accretion process near the regular black holes. We also study the behavior of radial velocity, energy density and rate of change of mass for each regular black holes.
The local density of optical states of a metasurface
Lunnemann, Per
2016-01-01
While metamaterials are often desirable for near-field functions, such as perfect lensing, or cloaking, they are often quantified by their response to plane waves from the far field. Here, we present a theoretical analysis of the local density of states near lattices of discrete magnetic scatterers, i.e., the response to near field excitation by a point source. Based on a point-dipole theory using Ewald summation and an array scanning method, we can swiftly and semi-analytically evaluate the local density of states (LDOS) for magnetoelectric point sources in front of an infinite two-dimensional (2D) lattice composed of arbitrary magnetoelectric dipole scatterers. The method takes into account radiation damping as well as all retarded electrodynamic interactions in a self-consistent manner. We show that a lattice of magnetic scatterers evidences characteristic Drexhage oscillations. However, the oscillations are phase shifted relative to the electrically scattering lattice consistent with the difference expect...
Anomalous density of states in hybrid normalmetal–superconductor bilayers
Indian Academy of Sciences (India)
A K Gupta; L Crétinon; B Pannetier; H Courtois
2006-01-01
In contact with a superconductor, the Andreev reflection of the electronslocally modifies the N metal electronic properties, including the local density of states(LDOS). We investigated the LDOS in superconductor–normal metal (Nb–Au) bilayersusing a very low temperature (60 mK) STM on the normal metal side. High resolutiontunneling spectra measured on the Au surface show a clear proximity effect with an energygap of reduced amplitude compared to the bulk Nb gap. The dependence of this mini-gap width with the normal metal thickness is discussed in terms of the Thouless energy. Within the mini-gap, the density of states does not reach zero and shows clear sub-gapfeatures. We compare the experimental spectra with the well-established quasi-classicaltheory.
Stronger Reflection from Black Hole Accretion Disks in Soft X-ray States
Steiner, James F; Garcia, Javier A; McClintock, Jeffrey E
2016-01-01
We analyze 15,000 spectra of 29 stellar-mass black hole candidates collected over the 16-year mission lifetime of RXTE using a simple phenomenological model. As these black holes vary widely in luminosity and progress through a sequence of spectral states, which we broadly refer to as hard and soft, we focus on two spectral components: The Compton power law and the reflection spectrum it generates by illuminating the accretion disk. Our proxy for the strength of reflection is the equivalent width of the Fe-K line as measured with respect to the power law. A key distinction of our work is that for all states we estimate the continuum under the line by excluding the thermal disk component and using only the component that is responsible for fluorescing the Fe-K line, namely the Compton power law. We find that reflection is several times more pronounced (~3) in soft compared to hard spectral states. This is most readily caused by the dilution of the Fe line amplitude from Compton scattering in the corona, which ...
Hot accretion flow with radiative cooling: state transitions in black hole X-ray binaries
Wu, Mao-Chun; Yuan, Ye-Fei; Gan, Zhao-Ming
2016-01-01
We investigate state transitions in black hole X-ray binaries through different parameters by using two-dimensional axisymmetric hydrodynamical simulation method. For radiative cooling in hot accretion flow, we take into account the bremsstrahlung, synchrotron and synchrotron-self Comptonization self-consistently in the dynamics. Our main result is that the state transitions occur when the accretion rate reaches a critical value $\\dot M \\sim 3\\alpha\\ \\dot M_{\\rm Edd}$, above which cold and dense clumpy/filamentary structures are formed, embedded within the hot gas. We argued this mode likely corresponds to the proposed two-phase accretion model, which may be responsible for the intermediate state of black hole X-ray binaries. When the accretion rate becomes sufficiently high, the clumpy/filamentary structures gradually merge and settle down onto the mid-plane. Eventually the accretion geometry transforms to a disc-corona configuration. In summary our results are consistent with the truncated accretion scenari...
Density of states governs light scattering in photonic crystals
García, P D; Froufe-Pérez, Luis S; López, C
2008-01-01
We describe a smooth transition from (fully ordered) photonic crystal to (fully disordered) photonic glass that enables us to make an accurate measurement of the scattering mean free path in nanostructured media and, in turn, establishes the dominant role of the density of states. We have found one order of magnitude chromatic variation in the scattering mean free path in photonic crystals for just $\\sim 3%$ shift around the band-gap ($\\sim 27$ nm in wavelength).
On the density of states of circular graphene quantum dots
Chau Nguyen, H.; Nguyen, Nhung T. T.; Nguyen, V. Lien
2017-10-01
We suggest a simple approach to calculate the local density of states that effectively applies to any structure created by an axially symmetric potential on a continuous graphene sheet such as circular graphene quantum dots or rings. Calculations performed for the graphene quantum dot studied in a recent scanning tunneling microscopy measurement (Gutierrez et al 2016 Nat. Phys. 12 1069–75) show an excellent experimental-theoretical agreement.
Beltrami state in black-hole accretion disk: A magnetofluid approach.
Bhattacharjee, Chinmoy; Das, Rupam; Stark, David J; Mahajan, S M
2015-12-01
Using the magnetofluid unification framework, we show that the accretion disk plasma (embedded in the background geometry of a black hole) can relax to a class of states known as the Beltrami-Bernoulli (BB) equilibria. Modeling the disk plasma as a Hall magnetohydrodynamics (MHD) system, we find that the space-time curvature can significantly alter the magnetic (velocity) decay rates as we move away from the compact object; the velocity profiles in BB states, for example, deviate substantially from the predicted corresponding geodesic velocity profiles. These departures imply a rich interplay of plasma dynamics and general relativity revealed by examining the corresponding Bernoulli condition representing "homogeneity" of total energy. The relaxed states have their origin in the constraints provided by the two helicity invariants of Hall MHD. These helicities conspire to introduce an oscillatory length scale into the system that is strongly influenced by relativistic and thermal effects.
Does nest site availability limit the density of hole nesting birds in small woodland patches?
Directory of Open Access Journals (Sweden)
J. Loman
2006-11-01
Full Text Available By providing nest boxes, previous studies have shown that nest sites are in short supply and limit the populations of several small passerines, including the Great Tit Parus major, the Blue Tit P. caeruleus, and the Pied Flycatcher Ficedula hypoleuca. Can this influence their distribution over a range of small woodland patch sizes in a heterogeneous landscape? To investigate this, a study was conducted in a heterogeneous agricultural landscape, with a mixture of wooded patches and cropped fields, in southern Sweden. The descriptive part of the study involved mapping territories of the three species in 135 patches. These species avoided small (<1 ha, Pied Flycatcher or very small (<0.2 ha, the two tit species forest patches in this landscape. In an experimental part, a subset of 34 patches, 0.01 to 24 ha in size was used. Territories were mapped in a first year as a control. In a second year, patches were matched by size and vegetation and nest-boxes were provided in one patch of each pair. Territories were again mapped. Providing nestboxes increased the density of breeding Great Tits in patches of all sizes and expanded their use of very small patches. The nest-boxes increased the density of Pied Flycatchers in large patches but not in small patches. So, is the lack of territories in small patches due to shortage of nest sites? The outcome of the experiment suggests nest site limitation as a cause of the observed Great Tit discrimination against very small habitat patches. The lack of Pied Flycatchers in small patches must however have another basis than lack of nest sites. The effect of providing nest-boxes on Blue Tit distribution was inconclusive.
Molecular double core-hole electron spectroscopy for chemical analysis
Tashiro, Motomichi; Fukuzawa, Hironobu; Ueda, Kiyoshi; Buth, Christian; Kryzhevoi, Nikolai V; Cederbaum, Lorenz S
2010-01-01
We explore the potential of double core hole electron spectroscopy for chemical analysis in terms of x-ray two-photon photoelectron spectroscopy (XTPPS). The creation of deep single and double core vacancies induces significant reorganization of valence electrons. The corresponding relaxation energies and the interatomic relaxation energies are evaluated by CASSCF calculations. We propose a method how to experimentally extract these quantities by the measurement of single and double core-hole ionization potentials (IPs and DIPs). The influence of the chemical environment on these DIPs is also discussed for states with two holes at the same atomic site and states with two holes at two different atomic sites. Electron density difference between the ground and double core-hole states clearly shows the relaxations accompanying the double core-hole ionization. The effect is also compared with the sensitivity of single core hole ionization potentials (IPs) arising in single core hole electron spectroscopy. We have ...
Thermodynamical quantities around a RNAdS black hole
Institute of Scientific and Technical Information of China (English)
Mi Li-Qin; Li Zhong-Heng
2006-01-01
The entropy density, energy density, pressure and equation of state around the RNAdS black hole are calculated in the WKB approximation on the Teukolsky-type master equation. The appearance of spin-dependent terms is demonstrated. The existence of these terms shows that the black hole radiation is not exactly thermal radiation and the black hole entropy is not strictly proportional to the area of the event horizon.
The transition to the metallic state in low density hydrogen
Energy Technology Data Exchange (ETDEWEB)
McMinis, Jeremy; Morales, Miguel A. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Ceperley, David M. [Department of Physics, University of Illinois, Urbana, Illinois 61801 (United States); Kim, Jeongnim [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)
2015-11-21
Solid atomic hydrogen is one of the simplest systems to undergo a metal-insulator transition. Near the transition, the electronic degrees of freedom become strongly correlated and their description provides a difficult challenge for theoretical methods. As a result, the order and density of the phase transition are still subject to debate. In this work, we use diffusion quantum Monte Carlo to benchmark the transition between paramagnetic and anti-ferromagnetic body centered cubic atomic hydrogen in its ground state. We locate the density of the transition by computing the equation of state for these two phases and identify the phase transition order by computing the band gap near the phase transition. These benchmark results show that the phase transition is continuous and occurs at a Wigner-Seitz radius of r{sub s} = 2.27(3) a{sub 0}. We compare our results to previously reported density functional theory, Hedin’s GW approximation, and dynamical mean field theory results.
Hunter, Simon; Mottram, Alexander D.; Anthopoulos, Thomas D.
2016-07-01
The density of trap states (DOS) in organic p-type transistors based on the small-molecule 2,8-difluoro-5,11-bis(triethylsilylethynyl) anthradithiophene (diF-TES ADT), the polymer poly(triarylamine) and blends thereof are investigated. The DOS in these devices are measured as a function of semiconductor composition and operating temperature. We show that increasing operating temperature causes a broadening of the DOS below 250 K. Characteristic trap depths of ˜15 meV are measured at 100 K, increasing to between 20 and 50 meV at room-temperature, dependent on the semiconductor composition. Semiconductor films with high concentrations of diF-TES ADT exhibit both a greater density of trap states as well as broader DOS distributions when measured at room-temperature. These results shed light on the underlying charge transport mechanisms in organic blend semiconductors and the apparent freezing-out of hole conduction through the polymer and mixed polymer/small molecule phases at temperatures below 225 K.
The synchrotron boiler and the spectral states of black hole binaries
Malzac, Julien
2008-01-01
We study the effects of synchrotron self-absorption on the Comptonising electron distribution in the magnetised corona of accreting black holes. We solve the kinetic equations assuming that power is supplied to the coronal electrons through Coulomb collisions with a population of hot protons and/or through the injection of non-thermal energetic electrons by some unspecified acceleration process. We compute numerically the steady state particle distributions and escaping photon spectra. These numerical simulations confirm that synchrotron self-absorption, together with e-e Coulomb collisions, constitute an efficient thermalising mechanism for the coronal electrons. When compared to the data, they allow us to constrain the magnetic field and temperature of the hot protons in the corona independently of any dynamical accretion flow model or geometry. A preliminary comparison with the Low Hard State (LHS) spectrum of Cygnus X-1 indicates a magnetic field below equipartition with radiation, suggesting that the cor...
The Complexity of Quantum States and Transformations: From Quantum Money to Black Holes
Aaronson, Scott
2016-01-01
These are lecture notes from a weeklong course in quantum complexity theory taught at the Bellairs Research Institute in Barbados, February 21-25, 2016. The focus is quantum circuit complexity---i.e., the minimum number of gates needed to prepare a given quantum state or apply a given unitary transformation---as a unifying theme tying together several topics of recent interest in the field. Those topics include the power of quantum proofs and advice states; how to construct quantum money schemes secure against counterfeiting; and the role of complexity in the black-hole information paradox and the AdS/CFT correspondence (through connections made by Harlow-Hayden, Susskind, and others). The course was taught to a mixed audience of theoretical computer scientists and quantum gravity / string theorists, and starts out with a crash course on quantum information and computation in general.
Extreme states of matter high energy density physics
Fortov, Vladimir E
2016-01-01
With its many beautiful colour pictures, this book gives fascinating insights into the unusual forms and behaviour of matter under extremely high pressures and temperatures. These extreme states are generated, among other things, by strong shock, detonation and electric explosion waves, dense laser beams,electron and ion beams, hypersonic entry of spacecraft into dense atmospheres of planets, and in many other situations characterized by extremely high pressures and temperatures.Written by one of the world's foremost experts on the topic, this book will inform and fascinate all scientists dealing with materials properties and physics, and also serve as an excellent introduction to plasma-, shock-wave and high-energy-density physics for students and newcomers seeking an overview. This second edition is thoroughly revised and expanded, in particular with new material on high energy-density physics, nuclear explosions and other nuclear transformation processes.
Population densities of painted buntings in the southeastern United States
Meyers, J. Michael
2011-01-01
The eastern population trend of Passerina ciris (Painted Bunting) declined 3.5% annually during the first 30 yrs of the Breeding Bird Survey (BBS, 1966–1996). Recently, the US Fish and Wildlife Service listed Painted Buntings as a focal species. Surveys for this focal species for the next 10 yrs (BBS, 1997–2007), however, are too low (2 in young pine plantations to 42 per km2 in maritime shrub. Effective detection radii for habitats varied from 64 to 90 m and were slightly higher in developed than in undeveloped habitats. Distance sampling is recommended to determine densities of Painted Buntings; however, large sample sizes (70–100 detections/habitat type) are required to monitor Painted Bunting densities in most habitats in the Atlantic coastal region of the southeastern United States. Special attention should be given to maritime shrub habitats, which may be important to maintaining the Painted Bunting population in the southeastern US.
Equation of State in a Generalized Relativistic Density Functional Approach
Typel, Stefan
2015-01-01
The basic concepts of a generalized relativistic density functional approach to the equation of state of dense matter are presented. The model is an extension of relativistic mean-field models with density-dependent couplings. It includes explicit cluster degrees of freedom. The formation and dissolution of nuclei is described with the help of mass shifts. The model can be adapted to the description of finite nuclei in order to study the effect of $\\alpha$-particle correlations at the nuclear surface on the neutron skin thickness of heavy nuclei. Further extensions of the model to include quark degrees of freedom or an energy dependence of the nucleon self-energies are outlined.
Laboratory tests of low density astrophysical nuclear equations of state.
Qin, L; Hagel, K; Wada, R; Natowitz, J B; Shlomo, S; Bonasera, A; Röpke, G; Typel, S; Chen, Z; Huang, M; Wang, J; Zheng, H; Kowalski, S; Barbui, M; Rodrigues, M R D; Schmidt, K; Fabris, D; Lunardon, M; Moretto, S; Nebbia, G; Pesente, S; Rizzi, V; Viesti, G; Cinausero, M; Prete, G; Keutgen, T; El Masri, Y; Majka, Z; Ma, Y G
2012-04-27
Clustering in low density nuclear matter has been investigated using the NIMROD multidetector at Texas A&M University. Thermal coalescence modes were employed to extract densities, ρ, and temperatures, T, for evolving systems formed in collisions of 47A MeV (40)Ar+(112)Sn, (124)Sn and (64)Zn+(112)Sn, (124)Sn. The yields of d, t, (3)He, and (4)He have been determined at ρ=0.002 to 0.03 nucleons/fm(3) and T=5 to 11 MeV. The experimentally derived equilibrium constants for α particle production are compared with those predicted by a number of astrophysical equations of state. The data provide important new constraints on the model calculations.
Black hole bound states in AdS_3 x S^2
de Boer, Jan; El-Showk, Sheer; Messamah, Ilies; Bleeken, Dieter Van den
2008-01-01
We systematically construct the geometries dual to the 1+1 dimensional (0,4) conformal field theories that arise in the low-energy description of wrapped M5-branes in S^1 x CY_3 compactifications of M-theory. This includes a large number of multicentered black hole bound states asymptotic to AdS_3 x S^2. In addition, we find many geometries that develop multiple, mutually decoupled AdS_3 x S^2 throats. We argue there is a useful one to one correspondence between the connected components of the space of solutions and particular limits of type IIA attractor flow trees. We point out that there is a thermodynamic instability of small supersymmetric BTZ black holes to localization on the S^2, a supersymmetric and exactly solvable analog of the well known AdS-Schwarzschild localization instability, and identify this with the ``Entropy Enigma'' in four dimensions. We discuss the phase transition this suggests, and initiate the CFT interpretation of these results.
Energy Technology Data Exchange (ETDEWEB)
Yanagida, S.; Mizumoto, K.; Pac, C.
1986-02-19
The use of ZnS or CdS as photocatalysts induces an efficient cis-trans photoisomerization of simple alkenes, e.g., the 2-octenes, 3-hexen-1-ols, and methyl 9-octadecenoates in photostationary cis-trans ratios almost identical with the thermodynamic equilibrium ratios achieved by the phenylthio radical. Quantum yields for the cis-trans photoisomerization, phi/sub c-t/, exceed largely over unity. Mechanistic studies involving Stern-Volmer analyses, quenching effect of oxygen, and ESR analyses under band-gap irradiation of ZnS in methanol demonstrate that the photoisomerizations take place with high turnover numbers at active sites where trapped holes at surface states, i.e., sulfur radicals arising from Zn vacancies and/or interstitial sulfur on sulfide semiconductors, play decisive roles. A highly efficient catalysis occurs with ZnS sols prepared from polysulfide-containing Na/sub 2/S solution. The trapped-hole mechanism is further supported by the enhanced effect of water acting as a good electron acceptor as well as the quenching effect of diethylamine acting as an electron donor.
Galactic Black Holes in the Hard State: A Multi-Wavelength View of Accretion and Ejection
Kalemci; Tomsick, John A.; Migliari; Corbel; Markoff
2010-01-01
The canonical hard state is associated with emission from all three fundamental accretion components: the accretion disk, the hot accretion disk corona and the jet. On top of these, the hard state also hosts very rich temporal variability properties (low frequency QPOs in the PDS, time lags, long time scale evolution). Our group has been working on the major questions of the hard state both observationally (with mult i-wavelength campaigns using RXTE, Swift, Suzaku, Spitzer, VLA, ATCA, SMARTS) and theoretically (through jet models that can fit entire SEDs). Through spectral and temporal analysis we seek to determine the geometry of accretion components, and relate the geometry to the formation and emission from a jet. In this presentation I will review the recent contributions of our group to the field, including the Swift results on the disk geometry at low accretion rates, the jet model fits to the hard state SEDs (including Spitzer data) of GRO J1655-40, and the final results on the evolution of spectral (including X-ray, radio and infrared) and temporal properties of elected black holes in the hard states. I will also talk about impact of ASTROSAT to the science objective of our group.
Stronger Reflection from Black Hole Accretion Disks in Soft X-Ray States
Steiner, James F.; Remillard, Ronald A.; García, Javier A.; McClintock, Jeffrey E.
2016-10-01
We analyze 15,000 spectra of 29 stellar-mass black hole (BH) candidates collected over the 16 year mission lifetime of Rossi X-ray Timing Explorer using a simple phenomenological model. As these BHs vary widely in luminosity and progress through a sequence of spectral states, which we broadly refer to as hard and soft, we focus on two spectral components: the Compton power law and the reflection spectrum it generates by illuminating the accretion disk. Our proxy for the strength of reflection is the equivalent width of the Fe-K line as measured with respect to the power law. A key distinction of our work is that for all states we estimate the continuum under the line by excluding the thermal disk component and using only the component that is responsible for fluorescing the Fe-K line, namely, the Compton power law. We find that reflection is several times more pronounced (˜3) in soft compared to hard spectral states. This is most readily caused by the dilution of the Fe line amplitude from Compton scattering in the corona, which has a higher optical depth in hard states. Alternatively, this could be explained by a more compact corona in soft (compared to hard) states, which would result in a higher reflection fraction.
Kumar, Parvendra; Nakajima, Takashi
2016-07-01
We theoretically show that under the Faraday geometry fast and high-fidelity optical initialization of electron spin (ES) state in a semiconductor quantum dot (SQD) can be realized by utilizing the light-hole (LH)-trion states. Initialization is completed within the time scale of ten nanoseconds with high fidelity, and the initialization laser pulse can be linearly, right-circularly, or left-circularly polarized. Moreover, we demonstrate that the time required for initialization can be further shortened down to a few hundreds of picoseconds if we introduce a pillar-microcavity to promote the relaxation of a LH-trion state towards the desired ES state through the Purcell effect. We also clarify the role of heavy-hole and light-hole mixing induced transitions on the fidelity of ES state initialization.
Raman Cooling of Solids through Photonic Density of States Engineering
Chen, Yin-Chung
2015-01-01
The laser cooling of vibrational states of solids has been achieved through photoluminescence in rare-earth elements, optical forces in optomechanics, and the Brillouin scattering light-sound interaction. The net cooling of solids through spontaneous Raman scattering, and laser refrigeration of indirect band gap semiconductors, both remain unsolved challenges. Here, we analytically show that photonic density of states (DoS) engineering can address the two fundamental requirements for achieving spontaneous Raman cooling: suppressing the dominance of Stokes (heating) transitions, and the enhancement of anti-Stokes (cooling) efficiency beyond the natural optical absorption of the material. We develop a general model for the DoS modification to spontaneous Raman scattering probabilities, and elucidate the necessary and minimum condition required for achieving net Raman cooling. With a suitably engineered DoS, we establish the enticing possibility of refrigeration of intrinsic silicon by annihilating phonons from ...
Electronic density of states in sequence dependent DNA molecules
de Oliveira, B. P. W.; Albuquerque, E. L.; Vasconcelos, M. S.
2006-09-01
We report in this work a numerical study of the electronic density of states (DOS) in π-stacked arrays of DNA single-strand segments made up from the nucleotides guanine G, adenine A, cytosine C and thymine T, forming a Rudin-Shapiro (RS) as well as a Fibonacci (FB) polyGC quasiperiodic sequences. Both structures are constructed starting from a G nucleotide as seed and following their respective inflation rules. Our theoretical method uses Dyson's equation together with a transfer-matrix treatment, within an electronic tight-binding Hamiltonian model, suitable to describe the DNA segments modelled by the quasiperiodic chains. We compared the DOS spectra found for the quasiperiodic structure to those using a sequence of natural DNA, as part of the human chromosome Ch22, with a remarkable concordance, as far as the RS structure is concerned. The electronic spectrum shows several peaks, corresponding to localized states, as well as a striking self-similar aspect.
The local density of optical states of a metasurface
Lunnemann, Per; Koenderink, A. Femius
2016-02-01
While metamaterials are often desirable for near-field functions, such as perfect lensing, or cloaking, they are often quantified by their response to plane waves from the far field. Here, we present a theoretical analysis of the local density of states near lattices of discrete magnetic scatterers, i.e., the response to near field excitation by a point source. Based on a pointdipole theory using Ewald summation and an array scanning method, we can swiftly and semi-analytically evaluate the local density of states (LDOS) for magnetoelectric point sources in front of an infinite two-dimensional (2D) lattice composed of arbitrary magnetoelectric dipole scatterers. The method takes into account radiation damping as well as all retarded electrodynamic interactions in a self-consistent manner. We show that a lattice of magnetic scatterers evidences characteristic Drexhage oscillations. However, the oscillations are phase shifted relative to the electrically scattering lattice consistent with the difference expected for reflection off homogeneous magnetic respectively electric mirrors. Furthermore, we identify in which source-surface separation regimes the metasurface may be treated as a homogeneous interface, and in which homogenization fails. A strong frequency and in-plane position dependence of the LDOS close to the lattice reveals coupling to guided modes supported by the lattice.
The evolution of the disc variability along the hard state of the black hole transient GX 339-4
De Marco, B.; Ponti, G.; Muñoz-Darias, T.; Nandra, K.
2015-12-01
We report on the analysis of hard-state power spectral density function (PSD) of GX 339-4 down to the soft X-ray band, where the disc significantly contributes to the total emission. At any luminosity probed, the disc in the hard state is intrinsically more variable than in the soft state. However, the fast decrease of disc variability as a function of luminosity, combined with the increase of disc intensity, causes a net drop of fractional variability at high luminosities and low energies, which reminds the well-known behaviour of disc-dominated energy bands in the soft state. The peak frequency of the high-frequency Lorentzian (likely corresponding to the high-frequency break seen in active galactic nuclei, AGN) scales with luminosity, but we do not find evidence for a linear scaling. In addition, we observe that this characteristic frequency is energy dependent. We find that the normalization of the PSD at the peak of the high-frequency Lorentzian decreases with luminosity at all energies, though in the soft band this trend is steeper. Together with the frequency shift, this yields quasi-constant high-frequency (5-20 Hz) fractional rms at high energies, with less than 10 per cent scatter. This reinforces previous claims suggesting that the high-frequency PSD solely scales with black hole mass. On the other hand, this constancy breaks down in the soft band (where the scatter increases to ˜30 per cent). This is a consequence of the additional contribution from the disc component, and resembles the behaviour of optical variability in AGN.
Harsh-Environment Solid-State Gamma Detector for Down-hole Gas and Oil Exploration
Energy Technology Data Exchange (ETDEWEB)
Peter Sandvik; Stanislav Soloviev; Emad Andarawis; Ho-Young Cha; Jim Rose; Kevin Durocher; Robert Lyons; Bob Pieciuk; Jim Williams; David O' Connor
2007-08-10
The goal of this program was to develop a revolutionary solid-state gamma-ray detector suitable for use in down-hole gas and oil exploration. This advanced detector would employ wide-bandgap semiconductor technology to extend the gamma sensor's temperature capability up to 200 C as well as extended reliability, which significantly exceeds current designs based on photomultiplier tubes. In Phase II, project tasks were focused on optimization of the final APD design, growing and characterizing the full scintillator crystals of the selected composition, arranging the APD device packaging, developing the needed optical coupling between scintillator and APD, and characterizing the combined elements as a full detector system preparing for commercialization. What follows is a summary report from the second 18-month phase of this program.
Explosion and Final State of an Unstable Reissner-Nordström Black Hole.
Sanchis-Gual, Nicolas; Degollado, Juan Carlos; Montero, Pedro J; Font, José A; Herdeiro, Carlos
2016-04-08
A Reissner-Nordström black hole (BH) is superradiantly unstable against spherical perturbations of a charged scalar field enclosed in a cavity, with a frequency lower than a critical value. We use numerical relativity techniques to follow the development of this unstable system-dubbed a charged BH bomb-into the nonlinear regime, solving the full Einstein-Maxwell-Klein-Gordon equations, in spherical symmetry. We show that (i) the process stops before all the charge is extracted from the BH, and (ii) the system settles down into a hairy BH: a charged horizon in equilibrium with a scalar field condensate, whose phase is oscillating at the (final) critical frequency. For a low scalar field charge q, the final state is approached smoothly and monotonically. For large q, however, the energy extraction overshoots, and an explosive phenomenon, akin to a bosenova, pushes some energy back into the BH. The charge extraction, by contrast, does not reverse.
Pair density wave superconducting states and statistical mechanics of dimers
Soto Garrido, Rodrigo Andres
The following thesis is divided in two main parts. Chapters 2, 3 and 4 are devoted to the study of the so called pair-density-wave (PDW) superconducting state and some of its connections to electronic liquid crystal (ELC) phases, its topological aspects in a one dimensional model and its appearance in a quasi-one dimensional system. On the other hand, chapter 5 is focused on the investigation of the classical statistical mechanics properties of dimers, in particular, the dimer model on the Aztec diamond graph and its relation with the octahedron equation. In chapter 2 we present a theory of superconducting states where the Cooper pairs have a nonzero center-of-mass momentum, inhomogeneous superconducting states known as a pair-density-waves (PDWs) states. We show that in a system of spin-1/2 fermions in two dimensions in an electronic nematic spin-triplet phase where rotational symmetry is broken in both real and spin space PDW phases arise naturally in a theory that can be analysed using controlled approximations. We show that several superfluid phases that may arise in this phase can be treated within a controlled BCS mean field theory, with the strength of the spin-triplet nematic order parameter playing the role of the small parameter of this theory. We find that in a spin-triplet nematic phase, in addition to a triplet p-wave and spin-singlet d-wave (or s depending on the nematic phase) uniform superconducting states, it is also possible to have a d-wave (or s) PDW superconductor. The PDW phases found here can be either unidirectional, bidirectional, or tridirectional depending on the spin-triplet nematic phase and which superconducting channel is dominant. In addition, a triple-helix state is found in a particular channel. We show that these PDW phases are present in the weak-coupling limit, in contrast to the usual Fulde-Ferrell-Larkin-Ovchinnikov phases, which require strong coupling physics in addition to a large magnetic field (and often both). In chapter
Soderman, PO; Ringbom, A; Blomgren, J; Olsson, N; Nilsson, L; Bordewijk, JA; van't Hof, G; Hofstee, MA; van der Ploeg, H; van der Werf, SY; Krasznahorkay, A; Balanda, A; Chmielewska, D; Laurent, H
2001-01-01
Neutron decay of excited hole states and isobaric analog states (IAS) populated by the Sn-116(He-3,alpha) reaction at an energy of 102 MeV has been investigated. The alpha -particles were analysed in a magnetic spectrograph positioned at 1.4 degrees and detected with a multiwire drift chamber. Excit
Superconducting electron and hole lenses
Cheraghchi, H.; Esmailzadeh, H.; Moghaddam, A. G.
2016-06-01
We show how a superconducting region (S), sandwiched between two normal leads (N), in the presence of barriers, can act as a lens for propagating electron and hole waves by virtue of the so-called crossed Andreev reflection (CAR). The CAR process, which is equivalent to Cooper pair splitting into two N electrodes, provides a unique possibility of constructing entangled electrons in solid state systems. When electrons are locally injected from an N lead, due to the CAR and normal reflection of quasiparticles by the insulating barriers at the interfaces, sequences of electron and hole focuses are established inside another N electrode. This behavior originates from the change of momentum during electron-hole conversion beside the successive normal reflections of electrons and holes due to the barriers. The focusing phenomena studied here are fundamentally different from the electron focusing in other systems, such as graphene p-n junctions. In particular, due to the electron-hole symmetry of the superconducting state, the focusing of electrons and holes is robust against thermal excitations. Furthermore, the effects of the superconducting layer width, the injection point position, and barrier strength are investigated on the focusing behavior of the junction. Very intriguingly, it is shown that by varying the barrier strength, one can separately control the density of electrons or holes at the focuses.
Spatial structure and density of states of transmission eigenchannels
Shi, Zhou; Davy, Matthieu; Tian, Chushun; Genack, Azriel Z.
2016-03-01
We explore the spatial profile of the ensemble average of the energy density of eigenchannels of the transmission matrix within random diffusive media using computer simulations and nonperturbative diagrammatic technique. A symmetrical profile with a peak in the middle of the sample is found for the fully transmitting eigenchannel and is shown to be closely related to a position dependent diffusion coefficient of the open media. We show that the average spatial profile of each transmission eigenchannel when normalized by the profile of the completely transmitting eigenchannel depends only upon the value of transmission through the corresponding eigenchannel. A universal expression for the average spatial profile is given in terms of the auxiliary localization lengths determined from transmission eigenvalues and position dependent diffusion coefficient. These lengths were first introduced by Dorokhov to describe the scaling of transmission and conductance through disordered media. Though direct measurement of energy distribution within a scattering medium is generally difficult, we demonstrate in microwave measurements that the integrated energy density stored in the media of each eigenchannel can be determined from the measurements of spectra of the transmission matrix. The derivative of the composite phase of the eigenchannels with respect to the angular frequency yields the contribution to the density of states (DOS) from the individual transmission eigenchannels. This is proportional to integrated energy stored and the dwell time of the transmission eigenchannel. The DOS determined from the transmission eigenchannel is shown to be in good agreement with DOS obtained by analyzing the field spectra into quasi-normal modes of the open medium. These results provide a path towards controlling the energy deposition within a scattering medium.
Ground-State Density Profiles of One-Dimensional Bose Gases with Anisotropic Transversal Confinement
Institute of Scientific and Technical Information of China (English)
HAO Ya-Jiang
2011-01-01
We investigate the ground-state density distributions of interacting one-dimensional Bose gases with anisotropic transversal confinement.Combining the exact ground state energy density of homogeneous bose gases with local density approximation,we determine the density distribution in each interacting regime for different anisotropic parameters.It is shown that the transversal anisotropic parameter changes the density distribution obviously,and the observed density profiles on each orientation exhibit a difference of a factor.
Critical state model with anisotropic critical current density
Bhagwat, K V; Ravikumar, G
2003-01-01
Analytical solutions of Bean's critical state model with critical current density J sub c being anisotropic are obtained for superconducting cylindrical samples of arbitrary cross section in a parallel geometry. We present a method for calculating the flux fronts and magnetization curves. Results are presented for cylinders with elliptical cross section with a specific form of the anisotropy. We find that over a certain range of the anisotropy parameter the flux fronts have shapes similar to those for an isotropic sample. However, in general, the presence of anisotropy significantly modifies the shape of the flux fronts. The field for full flux penetration also depends on the anisotropy parameter. The method is extended to the case of anisotropic J sub c that also depends on the local field B, and magnetization hysteresis curves are presented for typical values of the anisotropy parameter for the case of |J sub c | that decreases exponentially with |B|.
Phonon density of states in nanocrystalline 57Fe
Indian Academy of Sciences (India)
Ranber Singh; S Prakash; R Meyer; P Entel
2003-03-01
The Born–von Karman model is used to calculate phonon density of states (DOS) of nanocrystalline bcc Fe. It is found that there is an anisotropic stiffening in the interatomic force constants and hence there is shrinking in the nearest-neighbour distances in the nanophase. This leads to additional vibrational modes above the bulk phonons near the bottom of the phonon band. It is found that the high energy phonon modes of nanophase Fe are the surface modes. The calculated phonon DOS closely agree with the experimental data except a peak at 37 meV. The calculated phonon dispersion relations are also compared with those of the bulk phonons and anomalous behaviour is discussed in detail. The speciﬁc heat in nanophase enhances as compared to bulk phase at low temperatures and the calculated Debye temperature agrees with the experimental results. It is predicted that the nanocrystalline Fe may consist of about 14 GPa pressure.
Transmission eigenchannels and the densities of states of random media
Davy, Matthieu; Genack, Azriel Z
2014-01-01
The flux transmitted through disordered samples in eigenchannels of transmission varies over a wide range with a small number of highly transmissive channels among a multitude of dark eigenchannels1-5. The probability distribution of these transmission eigenvalues determines the ability to manipulate the transmitted pattern of classical waves6-16 and to describe the statistics of transmission1-5,17. However, measurements of transmission eigenvalues have not shed light on the dynamics of these channels or on their contribution to the density of states (DOS), which gives the proclivity of a medium to emit radiation and store energy18-28. Here we show in microwave measurements and computer simulations that the contribution of each transmission eigenchannel to the DOS and the delay time in transmission is the derivative with angular frequency of a composite phase shift of the transmission eigenchannel. These results illuminate the relationships between scattering, stored energy and dynamics from the nuclear to ma...
The local density of optical states of a metasurface
DEFF Research Database (Denmark)
Hansen, Per Lunnemann; Koenderink, A. Femius
2016-01-01
While metamaterials are often desirable for near-field functions, such as perfect lensing, or cloaking, they are often quantified by their response to plane waves from the far field. Here, we present a theoretical analysis of the local density of states near lattices of discrete magnetic scatterers......-dimensional (2D) lattice composed of arbitrary magnetoelectric dipole scatterers. The method takes into account radiation damping as well as all retarded electrodynamic interactions in a self-consistent manner. We show that a lattice of magnetic scatterers evidences characteristic Drexhage oscillations. However......, the oscillations are phase shifted relative to the electrically scattering lattice consistent with the difference expected for reflection off homogeneous magnetic respectively electric mirrors. Furthermore, we identify in which source-surface separation regimes the metasurface may be treated as a homogeneous...
Enhancement of photonic density of states in finite graphene multilayers
DaSilva, Ashley M.; Chang, You-Chia; Norris, Ted; MacDonald, Allan H.
2013-11-01
We consider the optical properties of finite systems composed of a series of graphene sheets separated by thin dielectric layers. Because these systems respond as conductors to electric fields in the plane of the graphene sheets and as insulators to perpendicular electric fields, they can be expected to have properties similar to those of hyperbolic metamaterials. We show that under typical experimental conditions graphene/dielectric multilayers have enhanced Purcell factors, and enhanced photonic densities of states in both the terahertz (THz) and midinfrared (mid-IR) frequency range. These behaviors can be traced to the coupled plasmon modes of the multilayer graphene system. We show that these results can be obtained with just a few layers of graphene.
The String Density of States from The Convolution Theorem
Meana, M L; Peñalba, J P; Meana, Marco Laucelli; Peñalba, Jesús Puente
1997-01-01
We study the microcanonical density of states and the thermal properties of a bosonic string gas starting from a calculation of the Helmholtz free energy in the S-representation. By adding more and more strings to the single string system, we induce that, for infinite volume, there is no negative specific heat region but a transition at a finite value of the energy per string from the low energy regime to a region of infinite specific heat at the Hagedorn temperature. Forcing the description of this phase in terms of strings gives a picture in which there is a very fat string in a sea of low energetic ones. We argue that the necessary changing of this description should not change the fact that perturbatively $T_H$ is a maximum temperature of the system.
Radio Detections During Two State Transitions of the Intermediate-Mass Black Hole HLX-1
Webb, Natalie; Cseh, David; Lenc, Emil; Godet, Olivier; Barret, Didier; Corbel, Stephane; Farrell, Sean; Fender, Robert; Gehrels, Neil; Heywood, Ian
2012-01-01
Relativistic jets are streams of plasma moving at appreciable fractions of the speed of light. They have been observed from stellar-mass black holes (approx. 3 to 20 solar masses) as well as supermassive black holes (approx.. 10(exp 6) to 10(exp 9) Solar Mass) found in the centers of most galaxies. Jets should also be produced by intermediate-mass black holes (approx. 10(exp 2) to 10(exp 5) Solar Mass), although evidence for this third class of black hole has, until recently, been weak. We report the detection of transient radio emission at the location of the intermediate-mass black hole candidate ESO 243-49 HLX-1, which is consistent with a discrete jet ejection event. These observations also allow us to refine the mass estimate of the black hole to be between approx. 9 × 10(exp 3) Solar Mass and approx. 9 × 10(exp 4) Solar Mass.
Radio detections during two state transitions of the intermediate-mass black hole HLX-1.
Webb, Natalie; Cseh, David; Lenc, Emil; Godet, Olivier; Barret, Didier; Corbel, Stephane; Farrell, Sean; Fender, Robert; Gehrels, Neil; Heywood, Ian
2012-08-01
Relativistic jets are streams of plasma moving at appreciable fractions of the speed of light. They have been observed from stellar-mass black holes (~3 to 20 solar masses, M(⊙)) as well as supermassive black holes (~10(6) to 10(9) M(⊙)) found in the centers of most galaxies. Jets should also be produced by intermediate-mass black holes (~10(2) to 10(5) M(⊙)), although evidence for this third class of black hole has, until recently, been weak. We report the detection of transient radio emission at the location of the intermediate-mass black hole candidate ESO 243-49 HLX-1, which is consistent with a discrete jet ejection event. These observations also allow us to refine the mass estimate of the black hole to be between ~9 × 10(3) M(⊙) and ~9 × 10(4) M(⊙).
Anomalous Low States and Long Term Variability in the Black Hole Binary LMC X-3
Smale, Alan P.; Boyd, Patricia T.
2012-01-01
Rossi X-my Timing Explorer observations of the black hole binary LMC X-3 reveal an extended very low X-ray state lasting from 2003 December 13 until 2004 March 18, unprecedented both in terms of its low luminosity (>15 times fainter than ever before seen in this source) and long duration (approx 3 times longer than a typical low/hard state excursion). During this event little to no source variability is observed on timescales of approx hours-weeks, and the X-ray spectrum implies an upper limit of 1.2 x 10(exp 35) erg/s, Five years later another extended low state occurs, lasting from 2008 December 11 until 2009 June 17. This event lasts nearly twice as long as the first, and while significant variability is observed, the source remains reliably in the low/hard spectral state for the approx 188 day duration. These episodes share some characteristics with the "anomalous low states" in the neutron star binary Her X-I. The average period and amplitude of the Variability of LMC X-3 have different values between these episodes. We characterize the long-term variability of LMC X-3 before and after the two events using conventional and nonlinear time series analysis methods, and show that, as is the case in Her X-I, the characteristic amplitude of the variability is related to its characteristic timescale. Furthermore, the relation is in the same direction in both systems. This suggests that a similar mechanism gives rise to the long-term variability, which in the case of Her X-I is reliably modeled with a tilted, warped precessing accretion disk.
STEADY-STATE RELATIVISTIC STELLAR DYNAMICS AROUND A MASSIVE BLACK HOLE
Energy Technology Data Exchange (ETDEWEB)
Bar-Or, Ben; Alexander, Tal [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, P.O. Box 26, Rehovot 76100 (Israel)
2016-04-01
A massive black hole (MBH) consumes stars whose orbits evolve into the small phase-space volume of unstable orbits, the “loss cone,” which take them into the MBH, or close enough to interact strongly with it. The resulting phenomena, e.g., tidal heating and disruption, binary capture and hyper-velocity star ejection, gravitational wave (GW) emission by inspiraling compact remnants, or hydrodynamical interactions with an accretion disk, can produce observable signatures and thereby reveal the MBH, affect its mass and spin evolution, test strong gravity, and probe stars and gas near the MBH. These continuous stellar loss and resupply processes shape the central stellar distribution. We investigate relativistic stellar dynamics near the loss cone of a non-spinning MBH in steady state, analytically and by Monte Carlo simulations of the diffusion of the orbital parameters. These take into account Newtonian mass precession due to enclosed stellar mass, in-plane precession due to general relativity, dissipation by GW, uncorrelated two-body relaxation, correlated resonant relaxation (RR), and adiabatic invariance due to secular precession, using a rigorously derived description of correlated post-Newtonian dynamics in the diffusion limit. We argue that general maximal entropy considerations strongly constrain the orbital diffusion in steady state, irrespective of the relaxation mechanism. We identify the exact phase-space separatrix between plunges and inspirals, and predict their steady-state rates. We derive the dependence of the rates on the mass of the MBH, show that the contribution of RR in steady state is small, and discuss special cases where unquenched RR in restricted volumes of phase-space may affect the steady state substantially.
Dexter, J.; McKinney, J.C.; Markoff, S.; Tchekhovskoy, A.
2014-01-01
Magnetically arrested accretion discs (MADs), where the magnetic pressure in the inner disc is dynamically important, provide an alternative mechanism for regulating accretion to what is commonly assumed in black hole systems. We show that a global magnetic field inversion in the MAD state can destr
Bagus, Paul S.; Broer, R; Graaf, C. de; Nieuwpoort, W.C.
1999-01-01
The electronic structure of NiO, with emphasis on the Ni 3s-hole ionic states, is studied using non-orthogonal configuration interaction, NOCI, wavefunctions for an NiO6 model of the crystal. Orbital sets are relaxed, or optimized, separately for each configuration used in the NOCI and orbital
Density of Trap States and Auger-mediated Electron Trapping in CdTe Quantum-Dot Solids.
Boehme, Simon C; Azpiroz, Jon Mikel; Aulin, Yaroslav V; Grozema, Ferdinand C; Vanmaekelbergh, Daniël; Siebbeles, Laurens D A; Infante, Ivan; Houtepen, Arjan J
2015-05-13
Charge trapping is an ubiquitous process in colloidal quantum-dot solids and a major limitation to the efficiency of quantum dot based devices such as solar cells, LEDs, and thermoelectrics. Although empirical approaches led to a reduction of trapping and thereby efficiency enhancements, the exact chemical nature of the trapping mechanism remains largely unidentified. In this study, we determine the density of trap states in CdTe quantum-dot solids both experimentally, using a combination of electrochemical control of the Fermi level with ultrafast transient absorption and time-resolved photoluminescence spectroscopy, and theoretically, via density functional theory calculations. We find a high density of very efficient electron traps centered ∼0.42 eV above the valence band. Electrochemical filling of these traps increases the electron lifetime and the photoluminescence quantum yield by more than an order of magnitude. The trapping rate constant for holes is an order of magnitude lower that for electrons. These observations can be explained by Auger-mediated electron trapping. From density functional theory calculations we infer that the traps are formed by dicoordinated Te atoms at the quantum dot surface. The combination of our unique experimental determination of the density of trap states with the theoretical modeling of the quantum dot surface allows us to identify the trapping mechanism and chemical reaction at play during charge trapping in these quantum dots.
Black holes as self-sustained quantum states, and Hawking radiation
Casadio, Roberto; Micu, Octavian; Orlandi, Alessio
2014-01-01
We investigate the proposal that black holes are Bose-Einstein condensates of gravitons starting form the Klein-Gordon equation for a massless scalar (graviton) field coupled to a static matter current. The classical field reproduces the Newtonian potential generated by the matter source, and the corresponding quantum state is given by a coherent superposition of graviton modes with continuous occupation number. However, if the source is given by the scalar field state itself, one finds that (approximately) only one mode is allowed, and the gravitons approach a Bose-Einstein condensate confined in a region of the size of the Schwarzschild radius of the system. The latter is then shown to represent a proper horizon, by means of the horizon wave-function of this quantum system, with an uncertainty in the horizon radius naturally related with the typical energy of Hawking modes. We finally speculate about the phase transition that might occur during the gravitational collapse of a star, ideally represented by th...
Markowitz, A.; Uttley, P.
2005-01-01
We present a broadband power spectral density function (PSD) measured from extensive RXTE monitoring data of the low-luminosity AGN NGC 4258, which has an accurate, maser-determined black hole mass of (3.9 plus or minus 0.1) x 10(exp 7) solar mass. We constrain the PSD break time scale to be greater than 4.5 d at greater than 90% confidence, which appears to rule out the possibility that NGC 4258 is an analogue of black hole X-ray binaries (BHXRBs) in the high/soft state. In this sense, the PSD of NGC 4258 is different to that of some more-luminous Seyferts, which appear similar to the PSDs of high/soft state X-ray binaries. This result supports previous analogies between LLAGN and X-ray binaries in the low/hard state based on spectral energy distributions, indicating that the AGN/BHXRB analogy is valid across a broad range of accretion rates.
Zhao, Ying-Jie
2016-01-01
We have introduced an improved exponential GUP, derived the maximally localized states, calculated quantum corrections to the thermodynamic quantities of the Schwardzschild black hole in our previous work. In this paper we continue to investigate how the maximally localized states and thermodynamic quantities such as Hawking temperature, the entropy, the heat capacity, the evaporation rate, and the decay time change in the extreme case that the integer n in our GUP rises to infinity.
Ab initio modeling of steady-state and time-dependent charge transport in hole-only α-NPD devices
Liu, Feilong; Massé, Andrea; Friederich, Pascal; Symalla, Franz; Nitsche, Robert; Wenzel, Wolfgang; Coehoorn, Reinder; Bobbert, Peter A.
2016-12-01
We present an ab initio modeling study of steady-state and time-dependent charge transport in hole-only devices of the amorphous molecular semiconductor α-NPD [N ,N'-Di(1 -naphthyl)-N ,N'-diphenyl-(1 ,1'-biphenyl)-4 ,4'-diamine] . The study is based on the microscopic information obtained from atomistic simulations of the morphology and density functional theory calculations of the molecular hole energies, reorganization energies, and transfer integrals. Using stochastic approaches, the microscopic information obtained in simulation boxes at a length scale of ˜10 nm is expanded and employed in one-dimensional (1D) and three-dimensional (3D) master-equation modeling of the charge transport at the device scale of ˜100 nm. Without any fit parameter, predicted current density-voltage and impedance spectroscopy data obtained with the 3D modeling are in very good agreement with measured data on devices with different α-NPD layer thicknesses in a wide range of temperatures, bias voltages, and frequencies. Similarly good results are obtained with the computationally much more efficient 1D modeling after optimizing a hopping prefactor.
Charge Order Induced in an Orbital Density-Wave State
Singh, Dheeraj Kumar; Takimoto, Tetsuya
2016-04-01
Motivated by recent angle resolved photoemission measurements [D. V. Evtushinsky et al., Phys. Rev. Lett. 105, 147201 (2010)] and evidence of the density-wave state for the charge and orbital ordering [J. García et al., Phys. Rev. Lett. 109, 107202 (2012)] in La0.5Sr1.5MnO4, the issue of charge and orbital ordering in a two-orbital tight-binding model for layered manganite near half doping is revisited. We find that the charge order with the ordering wavevector 2{Q} = (π ,π ) is induced by the orbital order of d-/d+-type having B1g representation with a different ordering wavevector Q, where the orbital order as the primary order results from the strong Fermi-surface nesting. It is shown that the induced charge order parameter develops according to TCO - T by decreasing the temperature below the orbital ordering temperature TCO, in addition to the usual mean-field behavior of the orbital order parameter. Moreover, the same orbital order is found to stabilize the CE-type spin arrangement observed experimentally below TCE < TCO.
Dimensional Effects on Densities of States and Interactions in Nanostructures
Directory of Open Access Journals (Sweden)
Dick Rainer
2010-01-01
Full Text Available Abstract We consider electrons in the presence of interfaces with different effective electron mass, and electromagnetic fields in the presence of a high-permittivity interface in bulk material. The equations of motion for these dimensionally hybrid systems yield analytic expressions for Green’s functions and electromagnetic potentials that interpolate between the two-dimensional logarithmic potential at short distance, and the three-dimensional r−1 potential at large distance. This also yields results for electron densities of states which interpolate between the well-known two-dimensional and three-dimensional formulas. The transition length scales for interfaces of thickness L are found to be of order Lm/2m* for an interface in which electrons move with effective mass m*, and for a dielectric thin film with permittivity in a bulk of permittivity . We can easily test the merits of the formalism by comparing the calculated electromagnetic potential with the infinite series solutions from image charges. This confirms that the dimensionally hybrid models are excellent approximations for distances r ≳ L/2.
Dimensional Effects on Densities of States and Interactions in Nanostructures.
Dick, Rainer
2010-10-01
We consider electrons in the presence of interfaces with different effective electron mass, and electromagnetic fields in the presence of a high-permittivity interface in bulk material. The equations of motion for these dimensionally hybrid systems yield analytic expressions for Green's functions and electromagnetic potentials that interpolate between the two-dimensional logarithmic potential at short distance, and the three-dimensional r(-1) potential at large distance. This also yields results for electron densities of states which interpolate between the well-known two-dimensional and three-dimensional formulas. The transition length scales for interfaces of thickness L are found to be of order Lm/2m(*) for an interface in which electrons move with effective mass m(*), and Lϵ(*)/2ϵ for a dielectric thin film with permittivity ϵ(*) in a bulk of permittivity ϵ. We can easily test the merits of the formalism by comparing the calculated electromagnetic potential with the infinite series solutions from image charges. This confirms that the dimensionally hybrid models are excellent approximations for distances r ≳ L/2.
A disk-corona model for low/hard state of black hole X-ray binaries
Wang, Jiu-Zhou; Huang, Chang-Yin
2013-01-01
A disk-corona model for fitting low/hard (LH) state of associated steady jet of black hole X-ray binaries (BHXBs) is proposed based on the large-scale magnetic field configuration of the coexistence of the Blandford-Znajek (BZ) and Blandford-Payne (BP) processes,where the magnetic field configuration for the BP process is determined by the requirement of energy conversion from Poynting energy flux into kinetic energy flux in the jet. It is found that corona current is crucial to guarantee the consistency of the jet launching from accretion disk. The relative importance of the BZ to BP processes in powering jets from black hole accretion disk is discussed, and the LH state of several BHXBs is fitted based on our model.In addition, we suggest that magnetic field configuration could be regarded as the second parameter for governing the state transition of BHXBs.
Dexter, Jason; Markoff, Sera; Tchekhovskoy, Alexander
2013-01-01
Magnetically arrested accretion discs (MADs), where the magnetic pressure in the inner disc is dynamically important, provide an alternative mechanism for regulating accretion to what is commonly assumed in black hole systems. We show that a global magnetic field inversion in the MAD state can destroy the jet, significantly increase the accretion rate, and move the effective inner disc edge in to the marginally stable orbit. Reconnection of the MAD field in the inner radii launches a new type of transient outflow containing hot plasma generated by magnetic dissipation. This transient outflow can be as powerful as the steady magnetically-dominated Blandford-Znajek jet in the MAD state. The field inversion qualitatively describes many of the observational features associated with the high luminosity hard to soft state transition in black hole X-ray binaries: the jet line, the transient ballistic jet, and the drop in rms variability. These results demonstrate that the magnetic field configuration can influence t...
Chan, H S
2000-09-01
A well-established experimental criterion for two-state thermodynamic cooperativity in protein folding is that the van't Hoff enthalpy DeltaH(vH) around the transition midpoint is equal, or very nearly so, to the calorimetric enthalpy DeltaH(cal) of the entire transition. This condition is satisfied by many small proteins. We use simple lattice models to provide a statistical mechanical framework to elucidate how this calorimetric two-state picture may be reconciled with the hierarchical multistate scenario emerging from recent hydrogen exchange experiments. We investigate the feasibility of using inverse Laplace transforms to recover the underlying density of states (i.e., enthalpy distribution) from calorimetric data. We find that the constraint imposed by DeltaH(vH)/DeltaH(cal) approximately 1 on densities of states of proteins is often more stringent than other "two-state" criteria proposed in recent theoretical studies. In conjunction with reasonable assumptions, the calorimetric two-state condition implies a narrow distribution of denatured-state enthalpies relative to the overall enthalpy difference between the native and the denatured conformations. This requirement does not always correlate with simple definitions of "sharpness" of a transition and has important ramifications for theoretical modeling. We find that protein models that assume capillarity cooperativity can exhibit overall calorimetric two-state-like behaviors. However, common heteropolymer models based on additive hydrophobic-like interactions, including highly specific two-dimensional Gō models, fail to produce proteinlike DeltaH(vH)/DeltaH(cal) approximately 1. A simple model is constructed to illustrate a proposed scenario in which physically plausible local and nonlocal cooperative terms, which mimic helical cooperativity and environment-dependent hydrogen bonding strength, can lead to thermodynamic behaviors closer to experiment. Our results suggest that proteinlike thermodynamic
The negative energy density for a three-single-electron state in the Dirac field
Institute of Scientific and Technical Information of China (English)
Shu Wei-Xing; Yu Hong-Wei; Wu Pu-Xun
2004-01-01
We examine the energy density produced by a state vector which is the superposition of three single electron states in the Dirac field in the four-dimensional Minkowski spacetime. We derive the conditions on which the energy density can be negative. We then show that the energy density satisfies two quantum inequalities in the ultrarelativistic limit.
The Bisognano-Wichmann theorem for charged states and the conformal boundary of a black hole
Directory of Open Access Journals (Sweden)
Roberto Longo
2000-07-01
Full Text Available This note concerns the study of the incremental entropy of a quantum black hole, based on Operator Algebra methods. Our results are based on the results presented in the references [6,11,12,13].
On the variation of black hole accretion disc radii as a function of state and accretion rate
Cabanac, C; Dunn, R J H; Koerding, E G
2009-01-01
Black hole binary transients undergo dramatic evolution in their X-ray timing and spectral behaviour during outbursts. In recent years a paradigm has arisen in which "soft" X-ray states are associated with an inner disc radius at, or very close to, the innermost stable circular orbit (ISCO) around the black hole, while in "hard" X-ray states the inner edge of the disc is further from the black hole. Models of advective flows suggest that as the X-ray luminosity drops in hard states, the inner disc progressively recedes, from a few to hundreds gravitational radii. Recent observations which show broad iron line detections and estimates of the disc component strength suggest that a non-recessed disc could still be present in bright hard states. In this study we present a comprehensive analysis of the spectral components associated with the inner disc, utilising data from instruments with sensitive low-energy responses and including reanalyses of previously published results. A key component of the study is to fu...
Black hole entropy without brick walls
Xiang, L
2002-01-01
The properties of the thermal radiation are discussed by using the new equation of state density motivated by the generalized uncertainty relation in the quantum gravity. There is no burst at the last stage of the emission of a Schwarzshild black hole. When the new equation of state density is utilized to investigate the entropy of a scalar field outside the horizon of a static black hole, the divergence appearing in the brick wall model is removed, without any cutoff. The entropy proportional to the horizon area is derived from the contribution of the vicinity of the horizon.
Black hole entropy without brick walls
Xiang, Li
2002-07-01
The properties of the thermal radiation are discussed by using the new equation of state density motivated by the generalized uncertainty relation in the quantum gravity. There is no burst at the last stage of the emission of a Schwarzschild black hole. When the new equation of state density is utilized to investigate the entropy of a scalar field outside the horizon of a static black hole, the divergence appearing in the brick wall model is removed, without any cutoff. The entropy proportional to the horizon area is derived from the contribution of the vicinity of the horizon.
State-of-the-Art Report on Five-hole Pitot tube
Energy Technology Data Exchange (ETDEWEB)
Kwon, Hyuk; Hwang, D. H.; Seo, K. W
2007-03-15
Five-hole pitot tube is an effective detector that could measure a three dimensional average flow field on a complex geometry. At the present study, have been mainly used in the field of aerodynamics and nautics, the five-hole pitot tube is extensively investigated to apply on the nuclear engineering. Five-hole pitot tube could measure the three dimensional velocity to make use of a relationship between pressure energy and kinetic energy from Bernoulli's equation; therefore, the report shortly overviewed the definition, units, and transducers of pressure and then detaily was described about the pitot tube. For five-hole pitot tube, history, kinds and fabrication methods were briefly provided. The calibration methods for the five-hole pitot tube were deeply introduced in various methods according to simple concept but complex process. Additionally, causeses of detection errors and estimation of uncertainty were included in the present report. Optical measurement and how wire anemometers are difficult to detect the flow velocity under environmental such as tight lattice bundle geometry, dusty flow and high temperature fluid. One of alternatives to overcome the diffculty is the five-hole pitot tube.
Institute of Scientific and Technical Information of China (English)
舒维星; 吴普训; 余洪伟
2003-01-01
Negative energy density and the quantum inequality are examined for the Dirac field. A proof is given of the quantum inequality for negative energy densities in the massive Dirac field produced by the superposition of two single particle electron states.
Horowitz-Strominger Black Hole Entropy Without Brick Wall
Institute of Scientific and Technical Information of China (English)
ZHANG Li-Chun; ZHAO Ren; LIN Hai
2004-01-01
@@ A Horowitz-Strominger black hole is discussed through a new equation of state density motivated by the generalized uncertainty relation in quantum gravity. There is no burst in the last stage of emission from a HorowitzStrominger black hole. When the new equation of state density is used to investigate the entropy of bosonic field and fermionic field outside the horizon of a static Horowitz-Strominger black hole, the divergence that appears in the brick-wall model is removed without any cutoff. The entropy proportional to the horizon area is derived from the contribution in the vicinity of the horizon.
Spherically symmetric black-hole entropy without brick walls
Ren, Zhao; Yue-Qin, Wu; Li-Chun, Zhang
2003-11-01
Properties of the thermal radiation of black holes are discussed using a new equation of state density motivated by the generalized uncertainty relation in quantum gravity. There is no burst at the last stage of emission from a spherically symmetric black hole. When the new equation of state density is used to investigate the entropy of a bosonic field and fermionic field outside the horizon of a static spherically symmetric black hole, the divergence that appears in the brick-wall model is removed without any cutoff. The entropy proportional to the horizon area is derived from the contribution from the vicinity of the horizon.
Density of States FFA analysis of SU(3) lattice gauge theory at a finite density of color sources
Giuliani, Mario; Gattringer, Christof
2017-10-01
We present a Density of States calculation with the Functional Fit Approach (DoS FFA) in SU(3) lattice gauge theory with a finite density of static color sources. The DoS FFA uses a parameterized density of states and determines the parameters of the density by fitting data from restricted Monte Carlo simulations with an analytically known function. We discuss the implementation of DoS FFA and the results for a qualitative picture of the phase diagram in a model which is a further step towards implementing DoS FFA in full QCD. We determine the curvature κ in the μ-T phase diagram and find a value close to the results published for full QCD.
Density of Line Features in the Western United States
U.S. Geological Survey, Department of the Interior — Density of linear features, such as roads, power lines, telephone lines, and railroad tracks have been shown to influence synanthropic predator abundance patterns...
Okawa, Hirotada; Witek, Helvi; Cardoso, Vitor
2014-05-01
Fundamental fields are a natural outcome in cosmology and particle physics and might therefore serve as a proxy for more complex interactions. The equivalence principle implies that all forms of matter gravitate, and one therefore expects relevant, universal imprints of new physics in strong field gravity, such as that encountered close to black holes. Fundamental fields in the vicinities of supermassive black holes give rise to extremely long-lived, or even unstable, configurations, which slowly extract angular momentum from the black hole or simply evolve nonlinearly over long time scales, with important implications for particle physics and gravitational-wave physics. Here, we perform a fully nonlinear study of scalar-field condensates around rotating black holes. We provide novel ways to specify initial data for the Einstein—Klein—Gordon system, with potential applications in a variety of scenarios. Our numerical results confirm the existence of long-lived bar modes, which act as lighthouses for gravitational wave emission: the scalar field condenses outside the black hole geometry and acts as a constant frequency gravitational-wave source for very long time scales. This effect could turn out to be a potential signature of beyond standard model physics and also a promising source of gravitational waves for future gravitational-wave detectors.
Determination of the Density of Energy States in a Quantizing Magnetic Field for Model Kane
Directory of Open Access Journals (Sweden)
G. Gulyamov
2016-01-01
Full Text Available For nonparabolic dispersion law determined by the density of the energy states in a quantizing magnetic field, the dependence of the density of energy states on temperature in quantizing magnetic fields is studied with the nonquadratic dispersion law. Experimental results obtained for PbTe were analyzed using the suggested model. The continuous spectrum of the energy density of states at low temperature is transformed into discrete Landau levels.
Ronca, Enrico; Angeli, Celestino; Belpassi, Leonardo; De Angelis, Filippo; Tarantelli, Francesco; Pastore, Mariachiara
2014-09-09
Making use of the recently developed excited state charge displacement analysis [E. Ronca et al., J. Chem. Phys. 140, 054110 (2014)], suited to quantitatively characterize the charge fluxes coming along an electronic excitation, we investigate the role of the density relaxation effects in the overall description of electronically excited states of different nature, namely, valence, ionic, and charge transfer (CT), considering a large set of prototypical small and medium-sized molecular systems. By comparing the response densities provided by time-dependent density functional theory (TDDFT) and the corresponding relaxed densities obtained by applying the Z-vector postlinear-response approach [N. C. Handy and H. F. Schaefer, J. Chem. Phys. 81, 5031 (1984)] with those obtained by highly correlated state-of-the-art wave function calculations, we show that the inclusion of the relaxation effects is imperative to get an accurate description of the considered excited states. We also examine what happens at the quality of the response function when an increasing amount of Hartree-Fock (HF) exchange is included in the functional, showing that the usually improved excitation energies in the case of CT states are not always the consequence of an improved description of their overall properties. Remarkably, we find that the relaxation of the response densities is always able to reproduce, independently of the extent of HF exchange in the functional, the benchmark wave function densities. Finally, we propose a novel and computationally convenient strategy, based on the use of the natural orbitals derived from the relaxed TDDFT density to build zero-order wave function for multireference perturbation theory calculations. For a significant set of different excited states, the proposed approach provided accurate excitation energies, comparable to those obtained by computationally demanding ab initio calculations.
Band structure and density of states in FeAs-based superconductors
Kashurnikov, V. A.; Krasavin, A. V.
2015-09-01
The generalized quantum Monte Carlo algorithm was used to obtain one-particle excitation spectrum and electron density of states for two-dimensional FeAs-clusters modeling iron-based superconductors within the limits of the full two-orbital model. The calculations were performed for clusters with sizes up to 10×10 FeAs-cells. The excitation spectra were reconstructed from Matsubara Green's function. The spectral density of states and the total density of states near the Fermi level were obtained. The data are in accordance with known experimental results. The influence of the cluster size, temperature, and the interaction strength on the density of states was analysed.
Chen, Wei-Chih; Lee, Yi-Huan; Chen, Chia-Yuan; Kau, Kuo-Chang; Lin, Lu-Yin; Dai, Chi-An; Wu, Chun-Guey; Ho, Kuo-Chuan; Wang, Juen-Kai; Wang, Leeyih
2014-02-25
An all-conjugated diblock copolymer, poly(2,5-dihexyloxy-p-phenylene)-b-poly(3-hexylthiophene) (PPP-b-P3HT), was synthesized and applied as a hole transport material (HTM) for the fabrication of solid-state dye-sensitized solar cells (ss-DSCs). This copolymer is characterized by an enhanced crystallinity, enabling its P3HT component to self-organize into interpenetrated and long-range-ordered crystalline fibrils upon spin-drying and ultimately endowing itself to have a faster hole mobility than that of the parent P3HT homopolymer. Transient photovoltage measurements indicate that the photovoltaic cell based on PPP-b-P3HT as the HTM has a longer electron lifetime than that of the reference device based on P3HT homopolymer. Moreover, comparing the two ss-DSCs in terms of the electrochemical impedance spectra reveals that the electron density in the TiO2 conduction band is substantially higher in the PPP-b-P3HT device than in the P3HT cell. Above observations suggest that the PPP block facilitates an intimate contact between the copolymer and dye molecules absorbed on the nanoporous TiO2 layer, which significantly enhances the performance of the resulting device. Consequently, the PPP-b-P3HT ss-DSC exhibits a promising power conversion efficiency of 4.65%. This study demonstrates that conjugated block copolymers can function as superior HTMs of highly efficient ss-DSCs.
Energy Technology Data Exchange (ETDEWEB)
Hod, Shahar [The Ruppin Academic Center, Emeq Hefer (Israel); The Hadassah Academic College, Jerusalem (Israel)
2017-05-15
The quasi-bound states of charged massive scalar fields in the near-extremal charged Reissner-Nordstroem black-hole spacetime are studied analytically. These discrete resonant modes of the composed black-hole-field system are characterized by the physically motivated boundary condition of ingoing waves at the black-hole horizon and exponentially decaying (bounded) radial eigenfunctions at spatial infinity. Solving the Klein-Gordon wave equation for the linearized scalar fields in the black-hole spacetime, we derive a remarkably compact analytical formula for the complex frequency spectrum which characterizes the quasi-bound state resonances of the composed Reissner-Nordstroem-black-hole-charged-massive-scalar-field system. (orig.)
Mixed density wave state in quasi-2D organic conductor
Energy Technology Data Exchange (ETDEWEB)
Katono, K., E-mail: k_katono@eng.hokudai.ac.jp [Department of Applied Physics, Hokkaido University, Sapporo 060-8628 (Japan); Ichimura, K. [Department of Applied Physics, Hokkaido University, Sapporo 060-8628 (Japan); Center of Education and Research for Topological Science and Technology, Hokkaido University, Sapporo 060-8628 (Japan); Kawashima, Y.; Yamaya, K. [Department of Applied Physics, Hokkaido University, Sapporo 060-8628 (Japan); Tanda, S. [Department of Applied Physics, Hokkaido University, Sapporo 060-8628 (Japan); Center of Education and Research for Topological Science and Technology, Hokkaido University, Sapporo 060-8628 (Japan)
2012-06-01
The density wave phase of {alpha}-(BEDT-TTF){sub 2}KHg(SCN){sub 4} was investigated by transport properties and magnetic susceptibility. The density wave transition was observed as a broad increase at T{sub DW}=9 K by resistance measurement. Temperature dependence of the static magnetic susceptibility {chi} shows a large Curie tail below 100 K. By subtracting the Curie component, we found that the magnetic susceptibility increases like weak ferromagnetism with decreasing temperature below 7.4 K. The gradual increase of {chi} below T{sub DW} is not expected in simple CDW or SDW, where the magnetic susceptibility decreases with decreasing temperature due to the reduction of Pauli paramagnetic component. To explain the weak ferromagnetic behavior, we consider the coexistence of CDW and SDW. We propose a model of the mixed density wave, where CDW exists with antiferromagnetically coupled canting spins.
Mixed density wave state in quasi-2D organic conductor
Katono, K.; Ichimura, K.; Kawashima, Y.; Yamaya, K.; Tanda, S.
2012-06-01
The density wave phase of α-(BEDT-TTF)2KHg(SCN)4 was investigated by transport properties and magnetic susceptibility. The density wave transition was observed as a broad increase at TDW=9 K by resistance measurement. Temperature dependence of the static magnetic susceptibility χ shows a large Curie tail below 100 K. By subtracting the Curie component, we found that the magnetic susceptibility increases like weak ferromagnetism with decreasing temperature below 7.4 K. The gradual increase of χ below TDW is not expected in simple CDW or SDW, where the magnetic susceptibility decreases with decreasing temperature due to the reduction of Pauli paramagnetic component. To explain the weak ferromagnetic behavior, we consider the coexistence of CDW and SDW. We propose a model of the mixed density wave, where CDW exists with antiferromagnetically coupled canting spins.
Zhang, Tianxi
2014-06-01
The black hole universe model is a multiverse model of cosmology recently developed by the speaker. According to this new model, our universe is a fully grown extremely supermassive black hole, which originated from a hot star-like black hole with several solar masses, and gradually grew up from a supermassive black hole with million to billion solar masses to the present state with trillion-trillion solar masses by accreting ambient matter or merging with other black holes. The entire space is structured with infinite layers or universes hierarchically. The innermost three layers include the universe that we live, the inside star-like and supermassive black holes called child universes, and the outside space called mother universe. The outermost layer is infinite in mass, radius, and entropy without an edge and limits to zero for both the matter density and absolute temperature. All layers are governed by the same physics and tend to expand physically in one direction (outward or the direction of increasing entropy). The expansion of a black hole universe decreases its density and temperature but does not alter the laws of physics. The black hole universe evolves iteratively and endlessly without a beginning. When one universe expands out, a new similar one is formed from inside star-like and supermassive black holes. In each of iterations, elements are resynthesized, matter is reconfigurated, and the universe is renewed rather than a simple repeat. The black hole universe is consistent with the Mach principle, observations, and Einsteinian general relativity. It has only one postulate but is able to explain all phenomena occurred in the universe with well-developed physics. The black hole universe does not need dark energy for acceleration and an inflation epoch for flatness, and thus has a devastating impact on the big bang model. In this talk, I will present how this new cosmological model explains the various aspects of the universe, including the origin
Fabrication of hole-patterned TiO{sub 2} photoelectrodes for solid-state dye-sensitized solar cells
Energy Technology Data Exchange (ETDEWEB)
Park, Jung Tae; Roh, Dong Kyu; Patel, Rajkumar; Son, Kyung Jin; Koh, Won-Gun [Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Kim, Jong Hak, E-mail: jonghak@yonsei.ac.k [Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)
2010-12-15
We suggest a simple process to fabricate a hole-patterned TiO{sub 2} electrode for a solid-state dye-sensitized solar cell (DSSC) to enhance cell performance through interfacial properties of the electrode with the electrolyte with minimum dye loading. The method involves prepatterning of SU-8 photoresist on a conducting glass, followed by the deposition of a nanocrystalline TiO{sub 2} layer, calcination at 450 {sup o}C and characterization using scanning electron microscopy (SEM). Hole-patterned TiO{sub 2} photoelectrodes yielded better solar energy conversion efficiency per dye loading compared to a conventional non-patterned photoelectrode. For example, a 50 {mu}m hole-patterned DSSC exhibited 4.50% conversion efficiency in the solid state, which is comparable to an unpatterned flat TiO{sub 2} photoelectrode (4.57%) however the efficiency per dye loading of the former (0.986%/g) was much greater than that of the latter (0.898%/g). The improvement was attributed to improved transmittance through the electrode as well as better interfacial properties between the electrolyte and electrode, as confirmed by UV-visible spectroscopy and electrochemical impedance (EIS) analysis.
Foucart, Francois; Brege, Wyatt; Duez, Matthew D; Kasen, Daniel; Hemberger, Daniel A; Kidder, Lawrence E; Pfeiffer, Harald P; Scheel, Mark A
2016-01-01
Neutron star-black hole binaries are among the strongest sources of gravitational waves detectable by current observatories. They can also power bright electromagnetic signals (gamma-ray bursts, kilonovae), and may be a significant source of production of r-process nuclei. A misalignment of the black hole spin with respect to the orbital angular momentum leads to precession of that spin and of the orbital plane, and has a significant effect on the properties of the post-merger remnant and of the material ejected by the merger. We present a first set of simulations of precessing neutron star-black hole mergers using a hot, composition dependent, nuclear-theory based equation of state (DD2). We show that the mass of the remnant and of the dynamical ejecta are broadly consistent with the result of simulations using simpler equations of state, while differences arise when considering the dynamics of the merger and the velocity of the ejecta. We show that the latter can easily be understood from assumptions about ...
Directory of Open Access Journals (Sweden)
Bui Thanh-Tuan
2013-10-01
Full Text Available Issue from thin-film technologies, dye-sensitized solar cells have become one of the most promising technologies in the field of renewable energies. Their success is not only due to their low weight, the possibility of making large flexible surfaces, but also to their photovoltaic efficiency which are found to be more and more significant (>12% with a liquid electrolyte, >7% with a solid organic hole conductor. This short review highlights recent advances in the characteristics and use of low-molecular-weight glass-forming organic materials as hole transporters in all solid-state dye-sensitized solar cells. These materials must feature specific physical and chemical properties that will ensure both the operation of a photovoltaic cell and the easy implementation. This review is an english extended version based on our recent article published in Matériaux & Techniques 101, 102 (2013.
State of the Art in Photon-Density Estimation
DEFF Research Database (Denmark)
Hachisuka, Toshiya; Jarosz, Wojciech; Georgiev, Iliyan
2013-01-01
Photon-density estimation techniques are a popular choice for simulating light transport in scenes with complicated geometry and materials. This class of algorithms can be used to accurately simulate inter-reflections, caustics, color bleeding, scattering in participating media, and subsurface sc...
State of the Art in Photon Density Estimation
DEFF Research Database (Denmark)
Hachisuka, Toshiya; Jarosz, Wojciech; Bouchard, Guillaume
2012-01-01
Photon-density estimation techniques are a popular choice for simulating light transport in scenes with complicated geometry and materials. This class of algorithms can be used to accurately simulate inter-reflections, caustics, color bleeding, scattering in participating media, and subsurface sc...
State of the Art in Photon Density Estimation
DEFF Research Database (Denmark)
Hachisuka, Toshiya; Jarosz, Wojciech; Bouchard, Guillaume
2012-01-01
scattering. Since its introduction, photon-density estimation has been significantly extended in computer graphics with the introduction of: specialized techniques that intelligently modify the positions or bandwidths to reduce visual error using a small number of photons, approaches that eliminate error...
Okawa, Hirotada; Cardoso, Vitor
2014-01-01
Fundamental scalar fields are a proxy for more complex interactions, and also a crucial ingredient in cosmology and particle physics: fundamental scalar fields are one of the possible solutions to the dark matter puzzle, to realize the Peccei-Quinn mechanism in QCD or the string-axiverse scenario. The equivalence principle implies that all forms of matter gravitate, and one therefore expects relevant, universal imprints of new physics in strong field gravity, such as that encountered close to black holes. Scalar fields in the vicinities of supermassive black holes give rise to extremely long-lived, or even unstable, configurations which slowly extract angular momentum from the black hole or simply evolve non-linearly over long timescales, with important implications for particle physics and gravitational-wave physics. Here, we perform a full non-linear study of scalar-field condensates around rotating black holes. We provide novel ways to specify initial data for the Einstein-Klein-Gordon system, with potenti...
Institute of Scientific and Technical Information of China (English)
Guo Qin
2007-01-01
A density matrix is usually obtained by solving the Bloch equation, however only a few Hamiltonians' density matrices can be analytically derived. The density matrix for two interacting particles with kinetic coupling is hard to derive by the usual method due to this coupling; this paper solves this problem by using the bipartite entangled state representation.
Level density parameters from excitation cross sections of isomeric states
Skakun, E. A.; Batij, V. G.
1992-03-01
Cross section ratios were measured for the production of the isomeric pairs99m,gRh,101m,gRh,102m,gRh,104m,gRh and108m,gIn in the (p,n)-reaction,107m,gIn and109m,gIn in the ( p, γ)-reaction over the energy range up to 9 MeV, and116m,gSb and118m,gSb in the (α, n)-reaction up to 24 MeV. The experimental results for these nuclei as well as for other isometric pairs excited in the ( p, n)-reaction were analysed in the frame of the statistical model for extracting the level density parameter values in the vicinity of closed nucleon shells. The level density parameter behaviour is discussed in the range of nuclear mass numbers under study.
Density of states of Frenkel excitons in strongly disordered two-dimensional systems
Siemann, Robert; Boukahil, Abdelkrim
2014-03-01
We present the calculation of the density of states of Frenkel excitons in strongly disordered two-dimensional systems. A random distribution of transition frequencies with variance σ2 characterizes the disorder. The Coherent Potential Approximation (CPA) calculations show a strong dependence of the density of states (DOS) on the disorder parameter σ.
Fourier Path Integral Monte Carlo Method for the Calculation of the Microcanonical Density of States
Freeman, D L; Freeman, David L.
1994-01-01
Using a Hubbard-Stratonovich transformation coupled with Fourier path integral methods, expressions are derived for the numerical evaluation of the microcanonical density of states for quantum particles obeying Boltzmann statistics. A numerical algorithmis suggested to evaluate the quantum density of states and illustrated on a one-dimensional model system.
Kyutoku, Koutarou; Shibata, Masaru; Taniguchi, Keisuke
2011-01-01
We study the merger of black hole (BH)-neutron star (NS) binaries with a variety of BH spins aligned or anti-aligned with the orbital angular momentum, and with the mass ratio in the range MBH/MNS = 2--5, where MBH and MNS are the mass of the BH and NS, respectively. We model NS matter by systematically parametrized piecewise polytropic equations of state. The initial condition is computed in the puncture framework adopting an isolated horizon framework to estimate the BH spin and assuming an irrotational velocity field for the fluid inside the NS. Dynamical simulations are performed in full general relativity by an adaptive mesh refinement code, SACRA. The treatment of hydrodynamic equations and estimation of the disk mass are improved. We find that the NS is tidally disrupted irrespective of the mass ratio when the BH has a moderately large prograde spin, whereas only binaries with low mass ratios, MBH/MNS ~ 0.1 Msun, which is required by central engines of short gamma-ray bursts, if the BH spin is prograde...
Steady-state vortex-line density in turbulent He II counterflow
Ostermeier, R. M.; Cromar, M. W.; Donnelly, R. J.; Kittel, P.
1978-01-01
We have measured the steady-state vortex-line density in turbulent counterflow using a second-sound-burst technique as a local probe. Contrary to the Vinen theory and previous assumptions, we find substantial line-density inhomogeneity and strong departures from the predicted heat-current dependence. Anomalous behavior of the line density at higher heat currents provides evidence for a new secondary flow state.
Ghosh, Soumen; Sonnenberger, Andrew L; Hoyer, Chad E; Truhlar, Donald G; Gagliardi, Laura
2015-08-11
The correct description of charge transfer in ground and excited states is very important for molecular interactions, photochemistry, electrochemistry, and charge transport, but it is very challenging for Kohn-Sham (KS) density functional theory (DFT). KS-DFT exchange-correlation functionals without nonlocal exchange fail to describe both ground- and excited-state charge transfer properly. We have recently proposed a theory called multiconfiguration pair-density functional theory (MC-PDFT), which is based on a combination of multiconfiguration wave function theory with a new type of density functional called an on-top density functional. Here we have used MC-PDFT to study challenging ground- and excited-state charge-transfer processes by using on-top density functionals obtained by translating KS exchange-correlation functionals. For ground-state charge transfer, MC-PDFT performs better than either the PBE exchange-correlation functional or CASPT2 wave function theory. For excited-state charge transfer, MC-PDFT (unlike KS-DFT) shows qualitatively correct behavior at long-range with great improvement in predicted excitation energies.
New Constraints on the Black Hole Low/Hard State Inner Accretion Flow with NuSTAR
Miller, J M; Bachetti, M; Wilkins, D; Boggs, S E; Chistensen, F E; Craig, W W; Fabian, A C; Grefenstette, B W; Hailey, C J; Harrison, F A; Kara, E; King, A L; Stern, D K; Zhang, W W
2014-01-01
We report on an observation of the Galactic black hole candidate GRS 1739-278 during its 2014 outburst, obtained with NuSTAR. The source was captured at the peak of a rising "low/hard" state, at a flux of ~0.3 Crab. A broad, skewed iron line and disk reflection spectrum are revealed. Fits to the sensitive NuSTAR spectra with a number of relativistically blurred disk reflection models yield strong geometrical constraints on the disk and hard X-ray "corona". Two models that explicitly assume a "lamppost" corona find its base to have a vertical height above the black hole of h = 5 (+7, -2) GM/c^2 and h = 18 +/-4 GM/c^2 (90% confidence errors); models that do not assume a "lamppost" return emissivity profiles that are broadly consistent with coronae of this size. Given that X-ray microlensing studies of quasars and reverberation lags in Seyferts find similarly compact coronae, observations may now signal that compact coronae are fundamental across the black hole mass scale. All of the models fit to GRS 1739-278 f...
Melas-Kyriazi, John
2011-04-05
A detailed investigation of the effect of hole transport material (HTM) pore filling on the photovoltaic performance of solid-state dye-sensitized solar cells (ss-DSCs) and the specific mechanisms involved is reported. It is demonstrated that the efficiency and photovoltaic characteristics of ss-DSCs improve with the pore filling fraction (PFF) of the HTM, 2,2\\',7,7\\'-tetrakis-(N, N-di-p-methoxyphenylamine)9,9\\'-spirobifluorene(spiro-OMeTAD). The mechanisms through which the improvement of photovoltaic characteristics takes place were studied with transient absorption spectroscopy and transient photovoltage/photocurrent measurements. It is shown that as the spiro-OMeTAD PFF is increased from 26% to 65%, there is a higher hole injection efficiency from dye cations to spiro-OMeTAD because more dye molecules are covered with spiro-OMeTAD, an order-of-magnitude slower recombination rate because holes can diffuse further away from the dye/HTM interface, and a 50% higher ambipolar diffusion coefficient due to an improved percolation network. Device simulations predict that if 100% PFF could be achieved for thicker devices, the efficiency of ss-DSCs using a conventional rutheniumdye would increase by 25% beyond its current value. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
DEFF Research Database (Denmark)
Bel, M.C.; Rodriguez, J.; Sizun, P.
2004-01-01
We report the results of extensive high-energy observations of the X-ray transient and black hole candidate XTE J1720-318 performed with INTEGRAL, XMM-Newton and RXTE. The source, which underwent an X-ray outburst in 2003 January, was observed in February in a spectral state dominated by a soft......, typical of a black-hole binary in the so-called High/Soft State. We then followed the evolution of the source outburst over several months using the INTEGRAL Galactic Centre survey observations. The source became active again at the end of March: it showed a clear transition towards a much harder state...... of the black hole X-ray novae class which populate our galactic bulge and we discuss its properties in the frame of the spectral models used for transient black hole binaries....
Interior properties of five-dimensional Schwarzschild black hole
Hong, Soon-Tae
2014-01-01
We investigate inner structure of Schwarzschild black hole on a five-dimensional spacetime S^3xR^2. To do this, we exploit a f\\"unfbein scheme. In particular, we construct an equation of state of hydrostatic equilibrium for the five-dimensional Schwarzschild black hole, which is a five-dimensional version of the Tolman-Oppenheimer-Volkoff equation on four-dimensional manifold. We also investigate uniform density interior configuration of the five-dimensional black hole which consists of incompressible fluid of density, to find a general relativistic expression for pressure.
Directory of Open Access Journals (Sweden)
V.A. Sidorov, E.A. Ekimov, A.V. Rakhmanina, S.M. Stishov, E.D. Bauer and J.D. Thompson
2006-01-01
Full Text Available Diamonds, synthesized at high pressures and high temperatures in the presence of boron, are heavily hole-doped by incorporation of boron into the diamond lattice. These diamonds become superconducting below Tc=2–9 K. Synthesis in the systems B-C and B4C-C at P=9 GPa and T=2500–2800 K result in formation of polycrystalline carbonado-like material, whereas synthesis from B-C-H gives small single crystals and intergrowth plates. Dense superconducting bodies can be prepared by compacting these single crystal particles at P=8 GPa and T=1800 K. Specific heat and resistivity measurements in magnetic fields prove the bulk nature of superconductivity in all pressure-synthesized samples and provide a consistent set of materials parameters that favor a conventional weak-coupling electron–phonon interpretation of the superconducting mechanism at high hole doping. Schottky barrier tunneling conductance spectra, obtained with contacts fabricated at the surface of these hole-doped diamonds, indicate the appearance of superconducting gap below Tc.
Energy Technology Data Exchange (ETDEWEB)
Pandey, S K [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 017 (India); Kumar, Ashwani [School of Physics, Devi Ahilya University, Khandwa Road, Indore 452 017 (India); Chaudhari, S M [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 017 (India); Pimpale, A V [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 017 (India)
2006-02-01
Electronic states of PrCoO{sub 3} are studied using x-ray photoemission spectroscopy. The Pr 3d{sub 5/2} core level and valence band (VB) were recorded using an Mg K {alpha} source. The core level spectrum shows that the 3d{sub 5/2} level is split into two components of multiplicity four and two, respectively, due to coupling of the spin states of the hole in 3d{sub 5/2} with the Pr 4f hole spin state. The observed splitting is 4.5 eV. The VB spectrum is interpreted using density of states (DOS) calculations under LDA and LDA +U. It is noted that LDA is not sufficient to explain the observed VB spectrum. Inclusion of on-site Coulomb correlation for Co 3d electrons in LDA +U calculations gives DOS which is useful in qualitative explanation of the ground state. However, it is necessary to include interactions between Pr 4f electrons to get better agreement with the experimental VB spectrum. It is seen that the VB consists of Pr 4f, Co 3d and O 2p states. Pr 4f, Co 3d and O 2p bands are highly mixed, indicating strong hybridization of these three states. The band near the Fermi level has about equal contributions from Pr 4f and O 2p states with somewhat smaller contribution from Co 3d states. Thus in the Zaanen, Sawatzky and Allen scheme PrCoO{sub 3} can be considered as a charge transfer insulator. The charge transfer energy {delta} can be obtained using LDA DOS calculations and the Coulomb-exchange energy U{sup '} from LDA +U. The explicit values for PrCoO{sub 3} are {delta} = 3.9 eV and U{sup '} = 5.5 eV; the crystal field splitting and 3d bandwidth of Co ions are also found to be 2.8 and 1.8 eV, respectively.
Directory of Open Access Journals (Sweden)
Shahar Hod
2015-10-01
Full Text Available Rotating black holes can support quasi-stationary (unstable bound-state resonances of massive scalar fields in their exterior regions. These spatially regular scalar configurations are characterized by instability timescales which are much longer than the timescale M set by the geometric size (mass of the central black hole. It is well-known that, in the small-mass limit α≡Mμ≪1 (here μ is the mass of the scalar field, these quasi-stationary scalar resonances are characterized by the familiar hydrogenic oscillation spectrum: ωR/μ=1−α2/2n¯02, where the integer n¯0(l,n;α→0=l+n+1 is the principal quantum number of the bound-state resonance (here the integers l=1,2,3,… and n=0,1,2,… are the spheroidal harmonic index and the resonance parameter of the field mode, respectively. As it depends only on the principal resonance parameter n¯0, this small-mass (α≪1 hydrogenic spectrum is obviously degenerate. In this paper we go beyond the small-mass approximation and analyze the quasi-stationary bound-state resonances of massive scalar fields in rapidly-spinning Kerr black-hole spacetimes in the regime α=O(1. In particular, we derive the non-hydrogenic (and, in general, non-degenerate resonance oscillation spectrum ωR/μ=1−(α/n¯2, where n¯(l,n;α=(l+1/22−2mα+2α2+1/2+n is the generalized principal quantum number of the quasi-stationary resonances. This analytically derived formula for the characteristic oscillation frequencies of the composed black-hole-massive-scalar-field system is shown to agree with direct numerical computations of the quasi-stationary bound-state resonances.
Do, T; Yelda, S; Ghez, A M; Bullock, J; Kaplinghat, M; Lu, J R; Peter, A G H; Phifer, K
2013-01-01
We present 3D kinematic observations of stars within the central 0.5 pc of the Milky Way nuclear star cluster using adaptive optics imaging and spectroscopy from the Keck telescopes. Recent observations have shown that the cluster has a shallower surface density profile than expected for a dynamically relaxed cusp, leading to important implications for its formation and evolution. However, the true three dimensional profile of the cluster is unknown due to the difficulty in de-projecting the stellar number counts. Here, we use spherical Jeans modeling of individual proper motions and radial velocities to constrain for the first time, the de-projected spatial density profile, cluster velocity anisotropy, black hole mass ($M_\\mathrm{BH}$), and distance to the Galactic center ($R_0$) simultaneously. We find that the inner stellar density profile of the late-type stars, $\\rho(r)\\propto r^{-\\gamma}$ to have a power law slope $\\gamma=0.05_{-0.60}^{+0.29}$, much more shallow than the frequently assumed Bahcall $\\&am...
DEFF Research Database (Denmark)
Silva-Junior, Mario R.; Schreiber, Marko; Sauer, Stephan P. A.;
2008-01-01
Time-dependent density functional theory (TD-DFT) and DFT-based multireference configuration interaction (DFT/MRCI) calculations are reported for a recently proposed benchmark set of 28 medium-sized organic molecules. Vertical excitation energies, oscillator strengths, and excited-state dipole...... moments are computed using the same geometries (MP2/6-31G*) and basis set (TZVP) as in our previous ab initio benchmark study on electronically excited states. The results from TD-DFT (with the functionals BP86, B3LYP, and BHLYP) and from DFT/MRCI are compared against the previous high-level ab initio...
Density and Phase State of a Confined Nonpolar Fluid
Kienle, Daniel F.; Kuhl, Tonya L.
2016-07-01
Measurements of the mean refractive index of a spherelike nonpolar fluid, octamethytetracylclosiloxane (OMCTS), confined between mica sheets, demonstrate direct and conclusive experimental evidence of the absence of a first-order liquid-to-solid phase transition in the fluid when confined, which has been suggested to occur from previous experimental and simulation results. The results also show that the density remains constant throughout confinement, and that the fluid is incompressible. This, along with the observation of very large increases (many orders of magnitude) in viscosity during confinement from the literature, demonstrate that the molecular motion is limited by the confining wall and not the molecular packing. In addition, the recently developed refractive index profile correction method, which enables the structural perturbation inherent at a solid-liquid interface and that of a liquid in confinement to be determined independently, was used to show that there was no measurable excess or depleted mass of OMCTS near the mica surface in bulk films or confined films of only two molecular layers.
Direct cosmological simulations of the growth of black holes and galaxies
Di Matteo, Tiziana; Springel, Volker; Hernquist, Lars; Sijacki, Debora
2007-01-01
We investigate the coupled formation and evolution of galaxies and their embedded supermassive black holes using state-of-the-art hydrodynamic simulations of cosmological structure formation. For the first time, we self-consistently follow the dark matter dynamics, radiative gas cooling, star formation, as well as black hole growth and associated feedback processes, starting directly from initial conditions appropriate for the LambdaCDM cosmology. Our modeling of the black hole physics is based on an approach we have developed in simulations of isolated galaxy mergers. Here we examine: (i) the predicted global history of black hole mass assembly (ii) the evolution of the local black hole-host mass correlations and (iii) the conditions that allow rapid growth of the first quasars, and the properties of their hosts and descendants today. We find a total black hole mass density in good agreement with observational estimates. The black hole accretion rate density peaks at lower redshift and evolves more strongly ...
Wang-Landau algorithm for continuous models and joint density of states.
Zhou, Chenggang; Schulthess, T C; Torbrügge, Stefan; Landau, D P
2006-03-31
We present a modified Wang-Landau algorithm for models with continuous degrees of freedom. We demonstrate this algorithm with the calculation of the joint density of states of ferromagnet Heisenberg models and a model polymer chain. The joint density of states contains more information than the density of states of a single variable-energy, but is also much more time consuming to calculate. We present strategies to significantly speed up this calculation for large systems over a large range of energy and order parameter.
Wang-Landau Algorithm for Continuous Models and Joint Density of States
Zhou, Chenggang; Schulthess, T. C.; Torbrügge, Stefan; Landau, D. P.
2006-03-01
We present a modified Wang-Landau algorithm for models with continuous degrees of freedom. We demonstrate this algorithm with the calculation of the joint density of states of ferromagnet Heisenberg models and a model polymer chain. The joint density of states contains more information than the density of states of a single variable-energy, but is also much more time consuming to calculate. We present strategies to significantly speed up this calculation for large systems over a large range of energy and order parameter.
DEFF Research Database (Denmark)
Tendulkar, Shriharsh P.; Bachetti, Matteo; Tomsick, J.
2014-01-01
frequencies. The Lorentzian has a width of 2 Hz and a fractional rms of 25+/-3%. The hard power-law index, the high energy of the cutoff, and the level of variability all are consistent with properties expected for an accreting black hole in the hard state. While we cannot completely rule out the possibility...... of a low magnetic field neutron star, a black hole is more likely....
DEFF Research Database (Denmark)
Tendulkar, Shriharsh P.; Bachetti, Matteo; Tomsick, J.
2014-01-01
frequencies. The Lorentzian has a width of 2 Hz and a fractional rms of 25+/-3%. The hard power-law index, the high energy of the cutoff, and the level of variability all are consistent with properties expected for an accreting black hole in the hard state. While we cannot completely rule out the possibility...... of a low magnetic field neutron star, a black hole is more likely....
The soft spectral state of the black hole candidate IGR J17091-3624 observed by INTEGRAL and Swift
DEFF Research Database (Denmark)
Del Santo, M.; Kuulkers, E.; Bozzo, E.
2011-01-01
The currently on-going outburst of the black hole candidate (BHC) IGR J17091-3624 (ATel #3144, #3159, #3167) has been recently observed simultaneously with INTEGRAL and Swift. The source was in the IBIS FOV on 2011 Feb. 28 from 17:45 to 21:23 (UTC; exposure time 7.7 ks) during the Galactic Bulge......, a better description of the spectrum (confirmed by the F-test) can be obtained adding a disk black-body component (red. chi^2=1.1 (302 d.o.f.)). The fit of the joint XRT+IBIS/ISGRI broad-band spectrum (0.8-200 keV) gives an absorption column density of N_H=1.00+/-0.06, a disc black-body temperature of 1...
The soft spectral state of the black hole candidate IGR J17091-3624 observed by INTEGRAL and Swift
DEFF Research Database (Denmark)
Del Santo, M.; Kuulkers, E.; Bozzo, E.
2011-01-01
The currently on-going outburst of the black hole candidate (BHC) IGR J17091-3624 (ATel #3144, #3159, #3167) has been recently observed simultaneously with INTEGRAL and Swift. The source was in the IBIS FOV on 2011 Feb. 28 from 17:45 to 21:23 (UTC; exposure time 7.7 ks) during the Galactic Bulge......, a better description of the spectrum (confirmed by the F-test) can be obtained adding a disk black-body component (red. chi^2=1.1 (302 d.o.f.)). The fit of the joint XRT+IBIS/ISGRI broad-band spectrum (0.8-200 keV) gives an absorption column density of N_H=1.00+/-0.06, a disc black-body temperature of 1...
Black hole formation in a contracting universe
Quintin, Jerome
2016-01-01
We study the evolution of cosmological perturbations in a contracting universe. We aim to determine under which conditions density perturbations grow to form large inhomogeneities and collapse into black holes. Our method consists in solving the cosmological perturbation equations in complete generality for a hydrodynamical fluid. We then describe the evolution of the fluctuations over the different length scales of interest and as a function of the equation of state for the fluid, and we explore two different types of initial conditions: quantum vacuum and thermal fluctuations. We also derive a general requirement for black hole collapse on sub-Hubble scales, and we use the Press-Schechter formalism to describe the black hole formation probability. For a fluid with a small sound speed (e.g., dust), we find that both quantum and thermal initial fluctuations grow in a contracting universe, and the largest inhomogeneities that first collapse into black holes are of Hubble size and the collapse occurs well befor...
Steady-State Density Functional Theory for Non-equilibrium Quantum Systems
Shuanglong, Liu
Recently, electron transport properties of molecular junctions under finite bias voltages have attracted a lot of attention because of the potential application of molecular electronic devices. When a molecular junction is under zero bias voltage at zero temperature, it is in equilibrium ground state and all its properties can be solved by ground-state density functional theory (GS-DFT) where ground-state electron density determines everything. Under finite bias voltage, the molecular junction is in non-equilibrium steady state. According to Hershfield's non-equilibrium statistics, a system in non-equilibrium steady state corresponds to an effective equilibrium system. This correspondence provides the basis for the steady-state density functional theory (SS-DFT) which will be developed in this thesis. (Abstract shortened by UMI.).
Proton-hole and core-excited states in the semi-magic nucleus {sup 131}In{sub 82}
Energy Technology Data Exchange (ETDEWEB)
Taprogge, J. [Instituto de Estructura de la Materia, CSIC, Madrid (Spain); Universidad Autonoma de Madrid, Departamento de Fisica Teorica, Madrid (Spain); RIKEN Nishina Center, RIKEN, Saitama (Japan); Jungclaus, A. [Instituto de Estructura de la Materia, CSIC, Madrid (Spain); Grawe, H. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Borzov, I.N. [Kurchatov Institute, Moscow (Russian Federation); Joint Institute for Nuclear Research, Dubna (Russian Federation); Nishimura, S.; Doornenbal, P.; Soederstroem, P.A.; Baba, H.; Fukuda, N.; Inabe, N.; Isobe, T.; Kameda, D.; Kubo, T.; Shimizu, Y.; Suzuki, H.; Takeda, H.; Watanabe, H. [RIKEN Nishina Center, RIKEN, Saitama (Japan); Lorusso, G. [RIKEN Nishina Center, RIKEN, Saitama (Japan); National Physical Laboratory, NPL, Teddington, Middlesex (United Kingdom); University of Surrey, Department of Physics, Guildford (United Kingdom); Simpson, G.S.; Drouet, F. [LPSC, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, Grenoble Cedex (France); Sumikama, T. [Tohoku University, Department of Physics, Sendai, Miyagi (Japan); Xu, Z.Y.; Niikura, M. [University of Tokyo, Department of Physics, Tokyo (Japan); Browne, F. [RIKEN Nishina Center, RIKEN, Saitama (Japan); University of Brighton, School of Computing, Engineering and Mathematics, Brighton (United Kingdom); Gernhaeuser, R.; Steiger, K.; Muecher, D. [Technische Universitaet Muenchen, Physik Department E12, Garching (Germany); Gey, G. [RIKEN Nishina Center, RIKEN, Saitama (Japan); LPSC, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, Grenoble Cedex (France); Institut Laue-Langevin, B.P. 156, Grenoble Cedex 9 (France); Jung, H.S. [Chung-Ang University, Department of Physics, Seoul (Korea, Republic of); Kim, G.D.; Kwon, Y.K. [Institute for Basic Science, Rare Isotope Science Project, Daejeon (Korea, Republic of); Kim, Y.K. [Institute for Basic Science, Rare Isotope Science Project, Daejeon (Korea, Republic of); Hanyang University, Department of Nuclear Engineering, Seoul (Korea, Republic of); Kojouharov, I.; Kurz, N.; Schaffner, H. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Li, Z. [Peking University, School of Physics and State key Laboratory of Nuclear Physics and Technology, Beijing (China); Sakurai, H. [RIKEN Nishina Center, RIKEN, Saitama (Japan); University of Tokyo, Department of Physics, Tokyo (Japan); Vajta, Zs. [RIKEN Nishina Center, RIKEN, Saitama (Japan); MTA Atomki, P.O. Box 51, Debrecen (Hungary); Wu, J. [RIKEN Nishina Center, RIKEN, Saitama (Japan); Peking University, School of Physics and State key Laboratory of Nuclear Physics and Technology, Beijing (China); Yagi, A.; Nishibata, H.; Odahara, A. [Osaka University, Department of Physics, Toyonaka (Japan); Yoshinaga, K. [Tokyo University of Science, Department of Physics, Faculty of Science and Technology, Noda, Chiba (Japan); Benzoni, G. [INFN, Sezione di Milano, Milano (Italy); Boenig, S.; Ilieva, S.; Kroell, T. [Technische Universitaet Darmstadt, Institut fuer Kernphysik, Darmstadt (Germany); Chae, K.Y. [Sungkyunkwan University, Department of Physics, Suwon (Korea, Republic of); Coraggio, L.; Gargano, A. [Complesso Universitario di Monte S. Angelo, Istituto Nazionale di Fisica Nucleare, Napoli (Italy); Daugas, J.M. [CEA, DAM, DIF, Arpajon cedex (France); Gadea, A.; Montaner-Piza, A. [CSIC-Univ. of Valencia, Instituto de Fisica Corpuscular, Paterna (Spain); Itaco, N. [Seconda Universita di Napoli, Dipartimento di Matematica e Fisica, Caserta (Italy); Kondev, F.G. [Argonne National Laboratory, Nuclear Engineering Division, Argonne, IL (United States); Lane, G.J. [Australian National University, Department of Nuclear Physics, Research School of Physical Sciences and Engineering, Canberra (Australia); Moschner, K.; Wendt, A. [University of Cologne, IKP, Cologne (Germany); Naqvi, F. [Yale University, Wright Nuclear Structure Laboratory, New Haven, CT (United States); Orlandi, R. [K.U. Leuven, Instituut voor Kern- en StralingsFysica, Heverlee (Belgium); Japan Atomic Energy Agency, Advanced Science Research Center, Tokai, Ibaraki (Japan); Patel, Z.
2016-11-15
The β decay of the N = 83 nucleus {sup 131}Cd has been studied at the RIBF facility at the RIKEN Nishina Center. The main purpose of the study was to identify the position of the 1p{sub 3/2} and 0f{sub 5/2} proton-hole states and the energies of core-excited configurations in the semi-magic nucleus {sup 131}In. From the radiation emitted following the β decay, a level scheme of {sup 131}In was established and the β feeding to each excited state determined. Similarities between the single-particle transitions observed in the β decays of the N = 83 isotones {sup 132}In and {sup 131}Cd are discussed. Finally the excitation energies of several core-excited configurations in {sup 131}In are compared to QRPA and shell-model calculations. (orig.)
Proton-hole and core-excited states in the semi-magic nucleus 131In82
Energy Technology Data Exchange (ETDEWEB)
Taprogge, J.; Jungclaus, A.; Grawe, H.; Borzov, I. N.; Nishimura, S.; Doornenbal, P.; Lorusso, G.; Simpson, G. S.; Söderström, P. -A.; Sumikama, T.; Xu, Z. Y.; Baba, H.; Browne, F.; Fukuda, N.; Gernhäuser, R.; Gey, G.; Inabe, N.; Isobe, T.; Jung, H. S.; Kameda, D.; Kim, G. D.; Kim, Y. -K.; Kojouharov, I.; Kubo, T.; Kurz, N.; Kwon, Y. K.; Li, Z.; Sakurai, H.; Schaffner, H.; Shimizu, Y.; Steiger, K.; Suzuki, H.; Takeda, H.; Vajta, Zs.; Watanabe, H.; Wu, J.; Yagi, A.; Yoshinaga, K.; Benzoni, G.; Bönig, S.; Chae, K. Y.; Coraggio, L.; Daugas, J. -M.; Drouet, F.; Gadea, A.; Gargano, A.; Ilieva, S.; Itaco, N.; Kondev, F. G.; Kröll, T.; Lane, G. J.; Montaner-Pizá, A.; Moschner, K.; Mücher, D.; Naqvi, F.; Niikura, M.; Nishibata, H.; Odahara, A.; Orlandi, R.; Patel, Z.; Podolyák, Zs.; Wendt, A.
2016-11-01
The decay of the N = 83 nucleus Cd-131 has been studied at the RIBF facility at the RIKEN Nishina Center. The main purpose of the study was to identify the position of the and proton-hole states and the energies of core-excited configurations in the semi-magic nucleus In-131. From the radiation emitted following the decay, a level scheme of In-131 was established and the feeding to each excited state determined. Similarities between the single-particle transitions observed in the decays of the N = 83 isotones In-132 and Cd-131 are discussed. Finally the excitation energies of several core-excited configurations in In-131 are compared to QRPA and shell-model calculations.
Deposition of hole-transport materials in solid-state dye-sensitized solar cells by doctor-blading
Ding, I-Kang
2010-07-01
We report using doctor-blading to replace conventional spin coating for the deposition of the hole-transport material spiro-OMeTAD (2,20,7,70-tetrakis-(N, N-di-p-methoxyphenylamine)- 9,90-spirobifluorene) in solid-state dye-sensitized solar cells. Doctor-blading is a roll-to-roll compatible, large-area coating technique, is capable of achieving the same spiro-OMeTAD pore filling fraction as spin coating, and uses much less material. The average power conversion efficiency of solid-state dye-sensitized solar cells made from doctorblading is 3.0% for 2-lm thick films and 2.0% for 5-lm thick films, on par with devices made with spin coating. Directions to further improve the filling fraction are also suggested. © 2010 Elsevier B.V. All rights reserved.
High Energy Density Solid State Li-ion Battery with Enhanced Safety Project
National Aeronautics and Space Administration — We propose to develop an all solid state Li-ion battery which is capable of delivering high energy density, combined with high safety over a wide operating...
The Band-Edge Behavior of the Density of Surfacic States
Energy Technology Data Exchange (ETDEWEB)
Kirsch, Werner [Ruhr Universitaet Bochum, Fakultaet fuer Mathematik and SFB-TR 12 (Germany)], E-mail: werner.kirsch@rub.de; Klopp, Frederic [Universite de Paris-Nord, LAGA, UMR 7539 CNRS, Institut Galilee (France)], E-mail: klopp@math.univ-paris13.fr
2006-05-15
This paper is devoted to the asymptotics of the density of surfacic states near the spectral edges for a discrete surfacic Anderson model. Two types of spectral edges have to be considered: fluctuating edges and stable edges. Each type has its own type of asymptotics. In the case of fluctuating edges, one obtains Lifshitz tails the parameters of which are given by the initial operator suitably 'reduced' to the surface. For stable edges, the surface density of states behaves like the surface density of states of a constant (equal to the expectation of the random potential) surface potential. Among the tools used to establish this are the asymptotics of the surface density of states for constant surface potentials.
Continuity of the integrated density of states on random length metric graphs
Lenz, Daniel; Post, Olaf; Veselic', Ivan
2008-01-01
We establish several properties of the integrated density of states for random quantum graphs: Under appropriate ergodicity and amenability assumptions, the integrated density of states can be defined using an exhaustion procedure by compact subgraphs. A trace per unit volume formula holds, similarly as in the Euclidean case. Our setting includes periodic graphs. For a model where the edge length are random and vary independently in a smooth way we prove a Wegner estimate and related regularity results for the integrated density of states. These results are illustrated for an example based on the Kagome lattice. In the periodic case we characterise all compactly supported eigenfunctions and calculate the position and size of discontinuities of the integrated density of states.
Dynamics of Spontaneous Emission Controlled by Local Density of States in Photonic Crystals
DEFF Research Database (Denmark)
Lodahl, Peter; Nikolaev, Ivan S.; van Driel, A. Floris;
2006-01-01
We have measured time-resolved spontaneous emission from quantum dots in 3D photonic crystals. Due to the spatially dependent local density of states, the distribution of decay rates varies strongly with the photonic crystal lattice parameter.......We have measured time-resolved spontaneous emission from quantum dots in 3D photonic crystals. Due to the spatially dependent local density of states, the distribution of decay rates varies strongly with the photonic crystal lattice parameter....
Quantum Statistical Entropy of Five-Dimensional Black Hole
Institute of Scientific and Technical Information of China (English)
ZHAO Ren; WU Yue-Qin; ZHANG Sheng-Li
2006-01-01
The generalized uncertainty relation is introduced to calculate quantum statistic entropy of a black hole.By using the new equation of state density motivated by the generalized uncertainty relation, we discuss entropies of Bose field and Fermi field on the background of the five-dimensional spacetime. In our calculation, we need not introduce cutoff. There is not the divergent logarithmic term as in the original brick-wall method. And it is obtained that the quantum statistic entropy corresponding to black hole horizon is proportional to the area of the horizon. Further it is shown that the entropy of black hole is the entropy of quantum state on the surface of horizon. The black hole's entropy is the intrinsic property of the black hole. The entropy is a quantum effect. It makes people further understand the quantum statistic entropy.
DEFF Research Database (Denmark)
Bel, M.C.; Rodriguez, J.; Sizun, P.
2004-01-01
, typical of a black-hole binary in the so-called High/Soft State. We then followed the evolution of the source outburst over several months using the INTEGRAL Galactic Centre survey observations. The source became active again at the end of March: it showed a clear transition towards a much harder state...
Present-day stress state in the Outokumpu deep drill hole, Finland
Pierdominici, Simona; Ask, Maria; Kukkonen, Ilmo; Kueck, Jochem
2017-04-01
This study aims to investigate the present-day stress field in the Outokumpu area, eastern Finland, using interpretation of borehole failure on acoustic image logs in a 2516 m deep hole. Two main objectives of this study are: i. to constrain the orientation of maximum horizontal stress by mapping the occurrence of stress-induced deformation features using two sets of borehole televiewer data, which were collected in 2006 and 2011; and ii. to investigate whether any time dependent deformation of the borehole wall has occurred (creep). The Outokumpu deep hole was drilled during 2004-2005 to study deep structures and seismic reflectors within the Outokumpu formation and conducted within the International Continental Scientific Drilling Program (ICDP). The hole was continuously core-drilled into Paleoproterozoic formation of metasediments, ophiolite-derived altered ultrabasic rocks and pegmatitic granite. In 2006 and 2011 two downhole logging campaigns were performed by the Operational Support Group of ICDP to acquire a set of geophysical data. Here we focus on a specific downhole logging measurement, the acoustic borehole televiewer (BHTV), to determine the present-day stress field in the Outokumpu area. We constrain the orientation and magnitude of in situ stress tensor based on borehole wall failures detected along a 2516 m deep hole. Horizontal stress orientation was determined by interpreting borehole breakouts (BBs) and drilling-induced tensile fractures (DIFs) from BHTV logs. BBs are stress-induced enlargements of the borehole cross section and occur in two opposite zones at angles around the borehole where the wellbore stress concentration (hoop stress) exceeds the value required to cause compressive failure of intact rock. DIFs are caused by tensile failure of the borehole wall and form at two opposite spots on the borehole where the stress concentration is lower than the tensile strength of the rock. This occurs at angles 90° apart from the center of the
Petiteau, Antoine; Sesana, Alberto
2011-01-01
Gravitational wave signals from coalescing Massive Black Hole (MBH) binaries could be used as standard sirens to measure cosmological parameters. The future space based gravitational wave observatory Laser Interferometer Space Antenna (LISA) will detect up to a hundred of those events, providing very accurate measurements of their luminosity distances. To constrain the cosmological parameters we also need to measure the redshift of the galaxy (or cluster of galaxies) hosting the merger. This requires the identification of a distinctive electromagnetic event associated to the binary coalescence. However, putative electromagnetic signatures may be too weak to be observed. Instead, we study here the possibility of constraining the cosmological parameters by enforcing statistical consistency between all the possible hosts detected within the measurement error box of a few dozen of low redshift (z<3) events. We construct MBH populations using merger tree realizations of the dark matter hierarchy in a LambdaCDM ...
Primordial Black Hole Baryogenesis
Baumann, D; Turok, N G; Baumann, Daniel; Steinhardt, Paul J.; Turok, Neil
2007-01-01
We reconsider the possibility that the observed baryon asymmetry was generated by the evaporation of primordial black holes that dominated the early universe. We present a simple derivation showing that the baryon asymmetry is insensitive to the initial black hole density and the cosmological model but is sensitive to the temperature-dependence of the CP and baryon-violating (or lepton-violating) interactions. We also consider the possibility that black holes stop evaporating and form Planck-mass remnants that act as dark matter. We show that primordial black holes cannot simultaneously account for both the observed baryon asymmetry and the (remnant) dark matter density unless the magnitude of CP violation is much greater than expected from most particle physics models. Finally, we apply these results to ekpyrotic/cyclic models, in which primordial black holes may form when branes collide. We find that obtaining the observed baryon asymmetry is compatible with the other known constraints on parameters.
Andreo, Pedro; Benmakhlouf, Hamza
2017-02-01
A number of recent publications on small photon beam dosimetry aim at contributing to the understanding of the response of solid-state detectors in small fields. Some of them assign the difference in response to the mass density, or to the electron density, of the sensitive detector material relative to that of water. This work analyses the role of the mass and electron density (ρ,{{n}\\text{e}} ), density effect (δ) and mean excitation energy (I-value) of some detector materials in a 6 MV photon beam of 0.5 cm radius, its rationale being that the response of a detector depends critically on the stopping-power ratio detector-to-water. The influence on the detector response of volume scaling by electron density, and of electron single and multiple scattering, is also investigated. Detector materials are water, diamond and silicon, and additional materials are included for consistency in the analysis. A detailed analysis on the (ρ,I,δ ) dependence of stopping-power ratios shows that the density effect δ depends both on the electron density and on the I-value of the medium, but not on the mass density ρ alone as is usually assumed. This leads to a double dependence of stopping-power ratios on the I-value and questions the adequacy of a ‘density perturbation factor’ or of common interpretations of detector response in terms of ρ alone. Differences in response can be described in terms of the variation of stopping power ratios detector-to-water, mainly due to different I-values and to a lesser extent to different values of electron density. It is found that at low energies the trend of Monte Carlo-calculated electron fluence spectra inside the detector materials depends solely on their I-values. No dependence on mass density or density effect alone is observed at any energy. The trend of restricted-cema ratios to water (as a substitute of absorbed dose ratios) follows that of stopping-power ratios at 1 MeV, the most probable energy of differential
Energy Technology Data Exchange (ETDEWEB)
Wampler, William R.; Myers, Samuel M.; Modine, Normand A.
2017-09-01
The energy-dependent probability density of tunneled carrier states for arbitrarily specified longitudinal potential-energy profiles in planar bipolar devices is numerically computed using the scattering method. Results agree accurately with a previous treatment based on solution of the localized eigenvalue problem, where computation times are much greater. These developments enable quantitative treatment of tunneling-assisted recombination in irradiated heterojunction bipolar transistors, where band offsets may enhance the tunneling effect by orders of magnitude. The calculations also reveal the density of non-tunneled carrier states in spatially varying potentials, and thereby test the common approximation of uniform- bulk values for such densities.
Directory of Open Access Journals (Sweden)
Yan-Gang Miao
2015-01-01
Full Text Available As a generalized uncertainty principle (GUP leads to the effects of the minimal length of the order of the Planck scale and UV/IR mixing, some significant physical concepts and quantities are modified or corrected correspondingly. On the one hand, we derive the maximally localized states—the physical states displaying the minimal length uncertainty associated with a new GUP proposed in our previous work. On the other hand, in the framework of this new GUP we calculate quantum corrections to the thermodynamic quantities of the Schwardzschild black hole, such as the Hawking temperature, the entropy, and the heat capacity, and give a remnant mass of the black hole at the end of the evaporation process. Moreover, we compare our results with that obtained in the frameworks of several other GUPs. In particular, we observe a significant difference between the situations with and without the consideration of the UV/IR mixing effect in the quantum corrections to the evaporation rate and the decay time. That is, the decay time can greatly be prolonged in the former case, which implies that the quantum correction from the UV/IR mixing effect may give rise to a radical rather than a tiny influence to the Hawking radiation.
Energy Technology Data Exchange (ETDEWEB)
Kalamkar, M.; Klis, M. van der [Astronomical Institute, “Anton Pannekoek,” University of Amsterdam, Science Park 904, 1098 XH, Amsterdam (Netherlands); Reynolds, M. T.; Miller, J. M. [Department of Astronomy, University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109 (United States); Altamirano, D., E-mail: maithili@oa-roma.inaf.it [School of Physics and Astronomy, University of Southampton, Southampton, Hampshire SO17 1BJ (United Kingdom)
2015-03-20
We study the outbursts of the black hole X-ray binaries MAXI J1659-152, SWIFT J1753.5-0127, and GX 339-4 with the Swift X-ray Telescope (XRT). The bandpass of the XRT has access to emission from both components of the accretion flow: the accretion disk and the corona/hot flow. This allows a correlated spectral and variability study, with variability from both components of the accretion flow. We present for the first time a combined study of the evolution of spectral parameters (disk temperature and radius) and timing parameters (frequency and strength) of all power spectral components in different spectral states. Comparison of the correlations in different spectral states shows that the frequency and strength of the power spectral components exhibit dependencies on the disk temperature that are different in the (low-)hard and the hard-intermediate states (HIMSs); most of these correlations that are clearly observed in the HIMS (in MAXI J1659-152 and GX 339-4) are not seen in the (low-)hard state (in GX 339-4 and SWIFT J1753.5-0127). Also, the responses of the individual frequency components to changes in the disk temperature are markedly different from one component to the next. Hence, the spectral-timing evolution cannot be explained by a single correlation that spans both these spectral states. We discuss our findings in the context of the existing models proposed to explain the origin of variability.
Ground State Density Distribution of Bose-Fermi Mixture in a One-Dimensional Harmonic Trap
Institute of Scientific and Technical Information of China (English)
HAO Ya-Jiang
2011-01-01
By the density-functional calculation we investigate the ground-state properties of Bose-Fermi mixture confined in one-dimensional harmonic traps. The homogeneous mixture of bosons and polarized fermions with contact interaction can be exactly solved by the Bethe-ansatz method. After giving the exact formula of ground state energy density, we employ the local-density approximation to determine the density distribution of each component. It is shown that with the increase in interaction, the total density distribution evolves to Fermi-like distribution and the system exhibits phase separation between two components when the interaction is strong enough but finite. While in the infinite interaction limit both bosons and fermions display the completely same Fermi-like distributions and phase separation disappears.
Energy Technology Data Exchange (ETDEWEB)
Manzke, G.; Richter, F.; Semkat, D.; Burau, G.K.G.; Kieseling, F.; Stolz, H. [Institute of Physics, University of Rostock, 18051 Rostock (Germany)
2011-04-15
We present a theoretical analysis of the emission of localized excitons in GaAs-AlGaAs quantum wells, which shows a strong nonlinear behavior with increasing excitation. Considering the influence of dynamical screening both on the one-particle properties of carriers and on the whole spectrum of electron-hole pair states, we are able to explain the nonlinearity as a transition of the emission from excitonic to electron-hole pair states in the continuum (electron-hole plasma). Moreover, our theoretical approach based on the quasi-particle approximation for the carriers states and quantum kinetic effects in the screening describes the observed changes of the shift of the exciton energy from higher to lower energies at a temperature of T = 10 K (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Hole hopping rates in single strand oligonucleotides
Energy Technology Data Exchange (ETDEWEB)
Borrelli, Raffaele [Dipartimento di Scienze Agrarie, Forestali e Alimentari, Università di Torino, Largo Paolo Braccini 2, I-10095 Grugliasco, TO (Italy); Capobianco, Amedeo [Dipartimento di Chimica e Biologia, Università di Salerno, Via Giovanni Paolo II, I-84084 Fisciano, SA (Italy); Peluso, Andrea, E-mail: apeluso@unisa.it [Dipartimento di Chimica e Biologia, Università di Salerno, Via Giovanni Paolo II, I-84084 Fisciano, SA (Italy)
2014-08-31
Highlights: • DNA hole transfer rates have been computed. • Delocalized adenine domains significantly affect hole transfer rates in DNA. • Franck–Condon weighted density of state from DFT normal modes. • DNA application in molecular electronics. - Abstract: The rates of hole transfer between guanine and adenine in single strand DNA have been evaluated by using Fermi’s golden rule and Kubo’s generating function approach for the Franck–Condon weighted density of states. The whole sets of the normal modes and vibrational frequencies of the two nucleobases, obtained at DFT/B3LYP level of calculation, have been considered in computations. The results show that in single strand the pyramidalization/planarization mode of the amino groups of both nucleobases plays the major role. At room temperature, the Franck–Condon density of states extends over a wide range of hole site energy difference, 0–1 eV, giving some hints about the design of oligonucleotides of potential technological interest.
Analyzing Density Operator in Thermal State for Complicated Time-Dependent Optical Systems
Directory of Open Access Journals (Sweden)
Jeong Ryeol Choi
2014-01-01
Full Text Available Density operator of oscillatory optical systems with time-dependent parameters is analyzed. In this case, a system is described by a time-dependent Hamiltonian. Invariant operator theory is introduced in order to describe time-varying behavior of the system. Due to the time dependence of parameters, the frequency of oscillation, so-called a modified frequency of the system, is somewhat different from the natural frequency. In general, density operator of a time-dependent optical system is represented in terms of the modified frequency. We showed how to determine density operator of complicated time-dependent optical systems in thermal state. Usually, density operator description of quantum states is more general than the one described in terms of the state vector.
Kluge, T.; Bussmann, M.; Chung, H.-K.; Gutt, C.; Huang, L. G.; Zacharias, M.; Schramm, U.; Cowan, T. E.
2016-03-01
Here, we propose to exploit the low energy bandwidth, small wavelength, and penetration power of ultrashort pulses from XFELs for resonant Small Angle Scattering (SAXS) on plasma structures in laser excited plasmas. Small angle scattering allows to detect nanoscale density fluctuations in forward scattering direction. Typically, the SAXS signal from laser excited plasmas is expected to be dominated by the free electron distribution. We propose that the ionic scattering signal becomes visible when the X-ray energy is in resonance with an electron transition between two bound states (resonant coherent X-ray diffraction). In this case, the scattering cross-section dramatically increases so that the signal of X-ray scattering from ions silhouettes against the free electron scattering background which allows to measure the opacity and derived quantities with high spatial and temporal resolution, being fundamentally limited only by the X-ray wavelength and timing. Deriving quantities such as ion spatial distribution, charge state distribution, and plasma temperature with such high spatial and temporal resolution will make a vast number of processes in shortpulse laser-solid interaction accessible for direct experimental observation, e.g., hole-boring and shock propagation, filamentation and instability dynamics, electron transport, heating, and ultrafast ionization dynamics.
Hu, Weifeng
2015-01-01
We describe and extend the formalism of state-specific analytic density matrix renormalization group (DMRG) energy gradients, first used by Liu et al (J. Chem. Theor.Comput. 9, 4462 (2013)). We introduce a DMRG wavefunction maximum overlap following technique to facilitate state-specific DMRG excited state optimization. Using DMRG configuration interaction (DMRG-CI) gradients we relax the low-lying singlet states of a series of trans-polyenes up to C20H22. Using the relaxed excited state geometries as well as correlation functions, we elucidate the exciton, soliton, and bimagnon ("single-fission") character of the excited states, and find evidence for a planar conical intersection.
Wang, Zhiqiang; Chakravarty, Sudip
2016-05-01
The Onsager rule determines the relationship between Fermi surface area and frequencies of quantum oscillations in magnetic fields. We show that this rule remains intact to an excellent approximation in the mixed-vortex state of the underdoped cuprates even though the Landau level index n may be fairly low, n ˜10 . The models we consider are fairly general, consisting of a variety of density wave states combined with d -wave superconductivity within a mean field theory. Vortices are introduced as quenched disorder and averaged over many realizations, which can be considered as snapshots of a vortex liquid state. We also show that the oscillations ride on top of a field independent density of states ρ (B ) for higher fields. This feature appears to be consistent with recent specific heat measurements [C. Marcenat et al., Nature Communications 6, 7927 (2015), 10.1038/ncomms8927]. The experimental data do not go to low fields at the lowest temperature 3 K. Thus, we cannot compare the density of state for the entire field range. Of course, the high temperature data are linear in the field at lower fields, as they should be, but our theory is only valid at very low temperatures, ideally at zero temperature. At lower fields and zero temperature we model the system as an ordered vortex lattice, and show that its density of states follows a dependence ρ (B ) ∝√{B } in agreement with the semiclassical results [JETP Lett 58, 469 (1993)].
Rusanov, Anatoly I
2004-07-22
A novel theory of an equation of state based on excluded volume and formulated in two preceding papers for gases and gaseous mixtures is extended to the entire density range by considering higher (beginning from the third) approximations of the theory. The algorithm of constructing higher approximations is elaborated. Equations of state are deduced using the requirement of maximum simplicity and contain a single free parameter to be chosen by reason of convenience or simplicity or to be used as a fitting parameter with respect to the computer simulation database. In this way, precise equations of state are derived for the hard-sphere fluid in the entire density range. On the side, the theory reproduces most known earlier equations of state for hard spheres and determines their place in the hierarchy of approximations. Equations of state for van der Waals fluids are also presented, and their critical parameters are estimated.
Black holes in an expanding universe.
Gibbons, Gary W; Maeda, Kei-ichi
2010-04-02
An exact solution representing black holes in an expanding universe is found. The black holes are maximally charged and the universe is expanding with arbitrary equation of state (P = w rho with -1 black hole temperature.
Density Matrix and Squeezed Vacuum State for General Coupling Harmonic Oscillator
Institute of Scientific and Technical Information of China (English)
SONG Tong-Qiang
2003-01-01
By taking a unitary transformation approach, we study two harmonic oscillators with both kinetic coupling and coordinate coupling terms, and derive the density matrix of the system. The results show that the ground state of the system is a rotated two single-mode squeezed state.
Magnetic edge states in MoS2 characterized using density-functional theory
DEFF Research Database (Denmark)
Vojvodic, Aleksandra; Hinnemann, B.; Nørskov, Jens Kehlet
2009-01-01
It is known that the edges of a two-dimensional slab of insulating MoS2 exhibit one-dimensional metallic edge states, the so-called "brim states." Here, we find from density-functional theory calculations that several edge structures, which are relevant for the hydrodesulfurization process, are m...
NuSTARand Swift observations of the very high state in GX 339-4: Weighing the black hole with X-rays
DEFF Research Database (Denmark)
Parker, M. L.; Tomsick, J. A.; Kennea, J. A.
2016-01-01
We present results from spectral fitting of the very high state of GX 339-4 with Nuclear Spectroscopic Telescope Array (NuSTAR) and Swift. We use relativistic reflection modeling to measure the spin of the black hole and inclination of the inner disk and find a spin of a = 0.95(-0.08)(+0.02) and ......We present results from spectral fitting of the very high state of GX 339-4 with Nuclear Spectroscopic Telescope Array (NuSTAR) and Swift. We use relativistic reflection modeling to measure the spin of the black hole and inclination of the inner disk and find a spin of a = 0...
NuSTARand Swift observations of the very high state in GX 339-4: Weighing the black hole with X-rays
DEFF Research Database (Denmark)
Parker, M. L.; Tomsick, J. A.; Kennea, J. A.
2016-01-01
We present results from spectral fitting of the very high state of GX 339-4 with Nuclear Spectroscopic Telescope Array (NuSTAR) and Swift. We use relativistic reflection modeling to measure the spin of the black hole and inclination of the inner disk and find a spin of a = 0.95(-0.08)(+0.02) and ......We present results from spectral fitting of the very high state of GX 339-4 with Nuclear Spectroscopic Telescope Array (NuSTAR) and Swift. We use relativistic reflection modeling to measure the spin of the black hole and inclination of the inner disk and find a spin of a = 0...
MAXI GSC observations of a spectral state transition in the black hole candidate XTE J1752-223
Nakahira, Satoshi; Sugizaki, Mutsumi; Ueda, Yoshihiro; Negoro, Hitoshi; Ebisawa, Ken; Kawai, Nobuyuki; Matsuoka, Masaru; Tsunemi, Hiroshi; Daikyuji, Arata; Eguchi, Satoshi; Hiroi, Kazuo; Ishikawa, Masaki; Ishiwata, Ryoji; Isobe, Naoki; Kawasaki, Kazuyoshi; Kimura, Masashi; Kohama, Mitsuhiro; Mihara, Tatehiro; Miyoshi, Sho; Morii, Mikio; Nakagawa, Yujin E; Nakajima, Motoki; Ozawa, Hiroshi; Sootome, Tetsuya; Sugimori, Kousuke; Suzuki, Motoko; Tomida, Hiroshi; Ueno, Shiro; Yamamoto, Takayuki; Yoshida, Atsumasa
2010-01-01
We present the first results on the black hole candidate XTE J1752-223 from the Gas Slit Camera (GSC) on-board the Monitor of All-sky X-ray Image (MAXI) on the International Space Station. Including the onset of the outburst reported by the Proportional Counter Array on-board the Rossi X-ray Timing Explorer on 2009 October 23, the MAXI/GSC has been monitoring this source approximately 10 times per day with a high sensitivity in the 2-20 keV band. XTE J1752-223 was initially in the low/hard state during the first 3 months. An anti-correlated behavior between the 2-4 keV and 4-20 keV bands were observed around January 20, 2010, indicating that the source exhibited the spectral transition to the high/soft state. A transient radio jet may have been ejected when the source was in the intermediate state where the spectrum was roughly explained by a power-law with a photon index of 2.5-3.0. The unusually long period in the initial low/hard state implies a slow variation in the mass accretion rate, and the dramatic s...
Kalamkar, M; van der Klis, M; Altamirano, D; Miller, J M
2015-01-01
We study the outbursts of the black hole X-ray binaries MAXI J1659-152, SWIFT J1753.5--0127 and GX 339-4 with the Swift X-ray Telescope. The bandpass of the X-ray Telescope has access to emission from both components of the accretion flow: the accretion disk and the corona/hot flow. This allows a correlated spectral and variability study, with variability from both components of the accretion flow. We present for the first time, a combined study of the evolution of spectral parameters (disk temperature and radius) and timing parameters (frequency and strength) of all power spectral components in different spectral states. Comparison of the correlations in different spectral states shows that the frequency and strength of the power spectral components exhibit dependencies on the disk temperature that are different in the (low-)hard and the hard-intermediate states; most of these correlations that are clearly observed in the hard-intermediate state (in MAXI J1659-152 and GX 339-4) are not seen in the (low-)hard...
Evidence for a change in the X-ray radiation mechanism in the hard state of Galactic black holes
Sobolewska, M A; Done, C; Malzac, J
2011-01-01
We present results on spectral variability of two Galactic black hole X-ray binaries, GRO J1655-40 and GX 339-4, in the hard state. We confirm a transition in behaviour of the photon index with luminosity, such that the well known decrease in X-ray photon index with decreasing luminosity only continues down to L_bol ~ 0.01 L_Edd . Below this point the photon index increases again. For Comptonisation models, this implies that the ratio of the Compton luminosity to seed photon luminosity, lh/ls, changes with bolometric luminosity, consistent with a scenario where seed photons change from cyclo-synchrotron at the lowest luminosities to those from a truncated disc. Alternatively, the transition could mark the point below which the non-thermal jet starts to dominate, or where reprocessed photons replace the viscous ones in an outflowing corona model.
Mishra, H; Mishra, Hiranmaya; Parikh, Jitendra C.
2001-01-01
We discuss in this note simultaneous existence of chiral symmetry breakingand color superconductivity at finite temperature and density in aNambu-Jona-Lasinio type model. The methodology involves an explicitconstruction of a variational ground state and minimisation of thethermodynamic potential. There appears to be a phase at finite densities withboth quark antiquark as well as diquark condensates for the "ground" state.Chiral symmetry breaking phase appear to catalyse the threshold for the diquarkcondensates to appear. We also compute the equation of state in this model.
Constraining the nuclear matter equation of state around twice saturation density
Directory of Open Access Journals (Sweden)
Leifels Y.
2015-01-01
Full Text Available Using data on elliptic flow measured by the FOPI collaboration we extract constraints for the equation of state (EOS of symmetric nuclear matter with the help of the microscopic transport code IQMD. Best agreement between data and calculations is obtained with a ’soft’ equation of state including a momentum dependent interaction. From the model it can be deduced that the characteristic density related to the observed flow signal is around twice saturation density and that both compression within the fireball and the presence of the surrounding spectator matter is necessary for the development of the signal and its sensitivity to the nuclear equation of state.
The Partial Density of States of CO2 Molecules Adsorption on the Fe (111) Surface
Wu, Junfang
2017-09-01
The state of CO2 molecules adsorption on Fe (111) surface is studied by simulation with the software, the partial density of states the adsorption is obtained. Through the graphical distribution, the pseudogap and the partial density of states at the Fermi level of the CO2 molecules adsorption on the Fe (111) surface is analyzed and compared. The key mechanism of CO2 molecules adsorption on the Fe (111) surface is revealed. The results showed that the CO2 molecules adsorption on the bridge position of Fe (111) surface is stable. The main reason of O atom and Fe atom combining with the bonding is that the resonance of the density of states happed between the O 2p orbital and Fe 3d orbital.
Chen, Mark S.
2013-12-26
Efficient charge carrier transport in organic field-effect transistors (OFETs) often requires thin films that display long-range order and close π-π packing that is oriented in-plane with the substrate. Although some polymers have achieved high field-effect mobility with such solid-state properties, there are currently few general strategies for controlling the orientation of π-stacking within polymer films. In order to probe structural effects on polymer-packing alignment, furan-containing diketopyrrolopyrrole (DPP) polymers with similar optoelectronic properties were synthesized with either linear hexadecyl or branched 2-butyloctyl side chains. Differences in polymer solubility were observed and attributed to variation in side-chain shape and polymer backbone curvature. Averaged field-effect hole mobilities of the polymers range from 0.19 to 1.82 cm2/V·s, where PDPP3F-C16 is the least soluble polymer and provides the highest maximum mobility of 2.25 cm2/V·s. Analysis of the films by AFM and GIXD reveal that less soluble polymers with linear side chains exhibit larger crystalline domains, pack considerably more closely, and align with a greater preference for in-plane π-π packing. Characterization of the polymer solutions prior to spin-coating shows a correlation between early onset nanoscale aggregation and the formation of films with highly oriented in-plane π-stacking. This effect is further observed when nonsolvent is added to PDPP3F-BO solutions to induce aggregation, which results in films with increased nanostructural order, in-plane π-π orientation, and field-effect hole mobilities. Since nearly all π-conjugated materials may be coaxed to aggregate, this strategy for enhancing solid-state properties and OFET performance has applicability to a wide variety of organic electronic materials. © 2013 American Chemical Society.
Strange matter equation of state in the quark mass-density-dependent model
Energy Technology Data Exchange (ETDEWEB)
Benvenuto, O.G. (Facultad de Ciencias Astronomicas y Geofisicas, Universidad Nacional de La Plata, Paseo del Bosque S/N, 1900 La Plata (Argentina)); Lugones, G. (Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 1900 La Plata (Argentina))
1995-02-15
We study the properties and stability of strange matter at [ital T]=0 in the quark mass-density-dependent model for noninteracting quarks. We found a wide stability window'' for the values of the parameters ([ital C],[ital M][sub [ital s]0]) and the resulting equation of state at low densities is stiffer than that of the MIT bag model. At high densities it tends to the ultrarelativistic behavior expected because of the asymptotic freedom of quarks. The density of zero pressure is near the one predicted by the bag model and [ital not] shifted away as stated before; nevertheless, at these densities the velocity of sound is [approx]50% larger in this model than in the bag model. We have integrated the equations of stellar structure for strange stars with the present equation of state. We found that the mass-radius relation is very much the same as in the bag model, although it extends to more massive objects, due to the stiffening of the equation of state at low densities.
Uncertainty relation and black hole entropy of Kerr spacetime
Institute of Scientific and Technical Information of China (English)
Hu Shuang-Qi; Zhao Ren
2005-01-01
The properties of thermal radiation are discussed by using a new equation of state density, which is motivated by the generalized uncertainty relation in the quantum gravity. There is no burst at the last stage of the emission of Kerr black hole. When the new equation of state density is utilized to investigate the entropy of a Bosonic field and Fermionic field outside the horizon of a static Kerr black hole, the divergence appearing in the brick wall model is removed, without any cutoff. The entropy proportional to the horizon area is derived from the contribution of the vicinity of the horizon.
Uncertainty relation and black hole entropy of Kerr spacetime
Hu, Shuang-Qi; Zhao, Ren
2005-07-01
The properties of thermal radiation are discussed by using a new equation of state density, which is motivated by the generalized uncertainty relation in the quantum gravity. There is no burst at the last stage of the emission of Kerr black hole. When the new equation of state density is utilized to investigate the entropy of a Bosonic field and Fermionic field outside the horizon of a static Kerr black hole, the divergence appearing in the brick wall model is removed, without any cutoff. The entropy proportional to the horizon area is derived from the contribution of the vicinity of the horizon.
Letter: Dilatonic Black Hole Entropy Without Brick Walls
Ren, Zhao; Sheng-Li, Zhang
2004-09-01
The properties of the thermal radiation are discussed by using the new equation of state density motivated by the generalized uncertainty relation in the quantum gravity. There is no burst at the last stage of the emission of dilatonic black hole. When the new equation of state density is utilized to investigate the entropy of a bosonic field and fermionic field outside the horizon of a static dilatonic black hole, the divergence appearing in the brick wall model is removed, without any cutoff. It is derived from the contribution of the vicinity of the horizon that the entropy is proportional to the horizon area.
Steady-state probability density function in wave turbulence under large volume limit
Institute of Scientific and Technical Information of China (English)
Yeontaek Choia; Sang Gyu Job
2011-01-01
We investigate the possibility for two-mode probability density function (PDF) to have a non-zero flux steady state solution. We take the large volume limit so that the space of modes becomes continuous. It is shown that in this limit all the steady-state two- or higher-mode PDFs are the product of one-mode PDFs. The flux of this steady-state solution turns out to be zero for any finite mode PDF.
Information entropy for static spherically symmetric black holes
Institute of Scientific and Technical Information of China (English)
Jiang Ji-Jian; Li Chuan-An
2009-01-01
By using the new equation of state density derived from the generalized uncertainty relation, the number of the quantum states near event horizon is obtained, with which then the information entropy of static spherically symmetric black holes has been discussed. It is found that the divergent integral of quantum states near the event horizon can be naturally avoided if using the new equation of state density without introducing the ultraviolet cut-off. The information entropy of black holes can be obtained precisely by the residue theorem, which is shown to be proportional to the horizon area. The information entropy of black holes obtained agrees with the Bechenstein-Hawking entropy when the suitable cutoff factor is adopted.
Thermo Vacuum State for Describing the Density Operator of Photon-subtracted Squeezed Chaotic Light
Wan, Zhi-Long; Fan, Hong-Yi; Li, Heng-Mei; Wang, Zhen
2017-10-01
For the density operator describing s-photon-subtracted squeezed chaotic light (PSSCL) we search for its thermo vacuum state (a pure state) in the real-fictitious space. We find that it reduces to a thermo vacuum state of squeezed chaotic light when s = 0, and to a thermo vacuum state of the optical negative binomial field when no squeezing. The new thermo vacuum state simplifies calculating photon number average, quantum fluctuation and Mandel's Q parameter of PSSCL. Using the method of integration within ordered product (IWOP) of operators we also derive the normalization coefficient and explicitly analytical expressions of Wigner function for PSSCL.
Di Cintio, Arianna; Tremmel, Michael; Governato, Fabio; Pontzen, Andrew; Zavala, Jesús; Bastidas Fry, Alexander; Brooks, Alyson; Vogelsberger, Mark
2017-08-01
We explore for the first time the effect of self-interacting dark matter (SIDM) on the dark matter (DM) and baryonic distribution in massive galaxies formed in hydrodynamical cosmological simulations, including explicit baryonic physics treatment. A novel implementation of supermassive black hole (SMBH) formation and evolution is used, as in Tremmel et al., allowing us to explicitly follow the SMBH dynamics at the centre of galaxies. A high SIDM constant cross-section is chosen, σ = 10 cm2gr-1, to amplify differences from CDM models. Milky Way-like galaxies form a shallower DM density profile in SIDM than they do in cold dark matter (CDM), with differences already at 20 kpc scales. This demonstrates that even for the most massive spirals, the effect of SIDM dominates over the adiabatic contraction due to baryons. Strikingly, the dynamics of SMBHs differs in the SIDM and reference CDM case. SMBHs in massive spirals have sunk to the centre of their host galaxy in both the SIDM and CDM run, while in less massive galaxies about 80 per cent of the SMBH population is off-centred in the SIDM case, as opposed to the CDM case in which ∼ 90 per cent of SMBHs have reached their host's centre. SMBHs are found as far as ∼9 kpc away from the centre of their host SIDM galaxy. This difference is due to the increased dynamical friction time-scale caused by the lower DM density in SIDM galaxies compared to CDM, resulting in core stalling. This pilot work highlights the importance of simulating in a full hydrodynamical context different DM models combined to the SMBH physics to study their influence on galaxy formation.
Modelling excited states of weakly bound complexes with density functional theory.
Briggs, Edward A; Besley, Nicholas A
2014-07-28
The binding within the ethene-argon and formaldehyde-methane complexes in the ground and electronically excited states is studied with equation of motion coupled cluster theory (EOM-CCSD), second-order Møller-Plesset perturbation theory (MP2) and density functional theory with dispersion corrections (DFT-D). Electronically excited states are studied within MP2 and Kohn-Sham DFT formalisms by exploiting a procedure called the maximum overlap method that allows convergence of the relevant self-consistent field equations to higher energy (or excited state) solutions. Potential energy curves computed using MP2 are in good agreement with the EOM-CCSD calculations for both the valence and Rydberg excited states studied. For the DFT-D approach, B3LYP-D3/aug-cc-pVTZ calculations are found to be in agreement with EOM-CCSD for the ground and valence excited states. However, for the π3s Rydberg state of ethene-argon and the n3s Rydberg state of formaldehyde-methane significant deviation is observed, and this disagreement with EOM-CCSD is present for a variety of DFT-D based approaches. Variation of the parameters within the D2 dispersion correction results in closer agreement with EOM-CCSD for the Rydberg states but demonstrates that a different parameterisation from the ground state is required for these states. This indicates that time-dependent density functional theory calculations based upon a DFT-D reference may be satisfactory for excitations to valence states, but will potentially be inaccurate for excitations to Rydberg states, or more generally states where the nature of the electron density is significantly different from the ground state.
Science Teacher, 2005
2005-01-01
Scientists using NASA's Swift satellite say they have found newborn black holes, just seconds old, in a confused state of existence. The holes are consuming material falling into them while somehow propelling other material away at great speeds. "First comes a blast of gamma rays followed by intense pulses of x-rays. The energies involved are much…
Density dependent magnetic field and the equation of state of hyperonic matter
Casali, Rudiney Hoffmann
2013-01-01
We are interested on the effects, caused by strong variable density dependent magnetic fields, on hyperonic matter, its symmetry energy, equations of state and mass-radius relations. The inclusion of the anomalous magnetic moment of the particles involved in a stellar system is performed, and some results are compared with the cases that do not take this correction under consideration. The Lagrangian density used follows the nonlinear Walecka model plus the leptons subjected to an external magnetic field.
Nuclear level densities with pairing and self-consistent ground-state shell effects
Arnould, M
1981-01-01
Nuclear level density calculations are performed using a model of fermions interacting via the pairing force, and a realistic single particle potential. The pairing interaction is treated within the BCS approximation with different pairing strength values. The single particle potentials are derived in the framework of an energy-density formalism which describes self-consistently the ground states of spherical nuclei. These calculations are extended to statistically deformed nuclei, whose estimated level densities include rotational band contributions. The theoretical results are compared with various experimental data. In addition, the level densities for several nuclei far from stability are compared with the predictions of a back-shifted Fermi gas model. Such a comparison emphasizes the possible danger of extrapolating to unknown nuclei classical level density formulae whose parameter values are tailored for known nuclei. (41 refs).
Saleh, Mahamat; Crepin, Kofane Timoleon
2016-01-01
We investigate thermodynamics and Phase transition of the Reissner-Nordstr\\"om black hole surrounded by quintessence. Using thermodynamical laws of black holes, we derive the expressions of some thermodynamics quantities for the Reissner-Nordstr\\"om black hole surrounded by quintessence. The variations of the temperature and heat capacity with the entropy were plotted for different values of the state parameter related to the quintessence, $\\omega_{q}$, and the normalization constant related to the density of quintessence $c$. We show that when varying the entropy of the black hole a phase transition is observed in the black hole. Moreover, when increasing the density of quintessence, the transition point is shifted to lower entropy and the temperature of the black hole decreases.
Spectral densities and diagrams of states of one-dimensional ionic Pauli conductor
Directory of Open Access Journals (Sweden)
O. Vorobyov
2011-06-01
Full Text Available We focus on the features of spectra and diagrams of states obtained via exact diagonalization technique for finite ionic conductor chain in periodic boundary conditions. One dimensional ionic conductor is described with the lattice model where ions are treated within the framework of "mixed" Pauli statistics. The ion transfer and nearest-neighbour interaction between ions are taken into account. The spectral densities and diagrams of states for various temperatures and values of interaction are obtained. The conditions of transition from uniform (Mott insulator to the modulated (charge density wave state through the superfluid-like state (similar to the state with the Bose-Einstein condensation observed in hard-core boson models are analyzed.
Whisker, Richard
2008-01-01
In this thesis we investigate black holes in the Randall-Sundrum braneworld scenario. We begin with an overview of extra-dimensional physics, from the original proposal of Kaluza and Klein up to the modern braneworld picture of extra dimensions. A detailed description of braneworld gravity is given, with particular emphasis on its compatibility with experimental tests of gravity. We then move on to a discussion of static, spherically symmetric braneworld black hole solutions. Assuming an equation of state for the ``Weyl term'', which encodes the effects of the extra dimension, we are able to classify the general behaviour of these solutions. We then use the strong field limit approach to investigate the gravitational lensing properties of some candidate braneworld black hole solutions. It is found that braneworld black holes could have significantly different observational signatures to the Schwarzschild black hole of standard general relativity. Rotating braneworld black hole solutions are also discussed, an...
Zhang, Hui
2015-01-01
Episodic jets are usually observed in the intermediate state of black hole transients during their X-ray outbursts. Here we report the discovery of a strong positive correlation between the peak radio power of the episodic jet $P_{\\rm jet}$ and the corresponding peak X-ray luminosity $L_{\\rm x}$ of the soft state (in Eddington units) in a complete sample of the outbursts of black hole transients observed during the RXTE era of which data are available, which follows the relation $\\log P_{\\rm jet}=(2.17\\pm{0.32})+(1.63\\pm0.24)\\times \\log {L_{\\rm x}}$. The transient ultra-luminous X-ray source in M31 and HLX-1 in EXO 243-49 fall on the relation if they contain stellar mass black hole and either stellar mass black hole or intermediate mass black hole, respectively. Besides, a significant correlation between the peak power of the episodic jet and the rate-of-increase of the X-ray luminosity $\\rm dL_{x}/dt$ during the rising phase of those outbursts is also found, following $\\log P_{\\rm jet}=(1.97\\pm{0.42})+(0.69\\...
An efficient algorithm for numerical computations of continuous densities of states
Langfeld, Kurt; Pellegrini, Roberto; Rago, Antonio
2015-01-01
In Wang-Landau type algorithms, Monte-Carlo updates are performed with respect to the density of states, which is iteratively refined during simulations. The partition function and thermodynamic observables are then obtained by standard integration. In this work, our recently introduced method in this class (the LLR approach) is analysed and further developed. Our approach is a histogram free method particularly suited for systems with continuous degrees of freedom giving rise to a continuum density of states, as it is commonly found in Lattice Gauge Theories and in some Statistical Mechanics systems. We show that the method possesses an exponential error suppression that allows us to estimate the density of states over several orders of magnitude with nearly-constant {\\it relative} precision. We explain how ergodicity issues can be avoided and how expectation values of arbitrary observables can be obtained within this framework. We then demonstrate the method using Compact U(1) Lattice Gauge Theory. A thorou...
DEFF Research Database (Denmark)
Nilsson, A.; Sthör, J.; Wiell, T.
1996-01-01
High-resolution L(3) x-ray absorption and emission spectra of Co and Cu in Co/Cu multilayers are shown to provide unique information on the occupied and unoccupied density of d states near buried interfaces. The d bands of both Co and Cu interfacial layers are shown to be considerably narrowed re...... relative to the bulk metals, and for Cu interface layers the d density of states is found to be enhanced near the Fermi level. The experimental results are confirmed by self-consistent electronic structure calculations.......High-resolution L(3) x-ray absorption and emission spectra of Co and Cu in Co/Cu multilayers are shown to provide unique information on the occupied and unoccupied density of d states near buried interfaces. The d bands of both Co and Cu interfacial layers are shown to be considerably narrowed...
Lattice Study of the High Density State of SU(2)-QCD
Muroya, S; Nonaka, C
2001-01-01
We investigate high density state of SU(2) QCD by using Lattice QCD simulation with Wilson fermions. The ratio of fermion determinants is evaluated at each step of the Metropol is link update by Woodbury formula. At $\\beta=0.7$, and $\\kappa = 0.150$, we calculate the baryon number density, the Polyakov lines, and the energy density of gluon sector with chemical potential $\\mu$=0 to 0.8 on the $4^{3} \\times 12$ lattice. Behavior of the meson propagators and diquark propagators with finite chemical potential are also investigated.
Distribution of local density of states in superstatistical random matrix theory
Energy Technology Data Exchange (ETDEWEB)
Abul-Magd, A.Y. [Department of Mathematics, Faculty of Science, Zagazig University, Zagazig (Egypt)]. E-mail: a_y_abul_magd@hotmail.com
2007-07-02
We expose an interesting connection between the distribution of local spectral density of states arising in the theory of disordered systems and the notion of superstatistics introduced by Beck and Cohen and recently incorporated in random matrix theory. The latter represents the matrix-element joint probability density function as an average of the corresponding quantity in the standard random-matrix theory over a distribution of level densities. We show that this distribution is in reasonable agreement with the numerical calculation for a disordered wire, which suggests to use the results of theory of disordered conductors in estimating the parameter distribution of the superstatistical random-matrix ensemble.
Feedback control of plasma density and heating power for steady state operation in LHD
Energy Technology Data Exchange (ETDEWEB)
Kamio, Shuji, E-mail: kamio@nifs.ac.jp; Kasahara, Hiroshi; Seki, Tetsuo; Saito, Kenji; Seki, Ryosuke; Nomura, Goro; Mutoh, Takashi
2015-12-15
Highlights: • We upgraded a control system for steady state operation in LHD. • This system contains gas fueling system and ICRF power control system. • Automatic power boost system is also attached for stable operation. • As a result, we achieved the long pulse up to 48 min in the electron density of more than 1 × 10{sup 19} m{sup −3}. - Abstract: For steady state operation, the feedback control of plasma density and heating power system was developed in the Large Helical Device (LHD). In order to achieve a record of the long pulse discharge, stable plasma density and heating power are needed. This system contains the radio frequency (RF) heating power control, interlocks, gas fueling, automatic RF phase control, ion cyclotron range of frequency (ICRF) antenna position control, and graphical user interface (GUI). Using the density control system, the electron density was controlled to the target density and using the RF heating power control system, the RF power injection could be stable. As a result of using this system, we achieved the long pulse up to 48 min in the electron density of more than 1 × 10{sup 19} m{sup −3}. Further, the ICRF hardware experienced no critical accidents during the 17th LHD experiment campaign in 2013.
Density and localized states' impact on amorphous carbon electron transport mechanisms
Caicedo-Dávila, S.; Lopez-Acevedo, O.; Velasco-Medina, J.; Avila, A.
2016-12-01
This work discusses the electron transport mechanisms that we obtained as a function of the density of amorphous carbon (a-C) ultra-thin films. We calculated the density of states (total and projected), degree of electronic states' localization, and transmission function using the density functional theory and nonequilibrium Green's functions method. We generated 25 sample a-C structures using ab-initio molecular dynamics within the isothermal-isobaric ensemble. We identified three transport regimes as a function of the density, varying from semimetallic in low-density samples ( ≤2.4 g/cm3) to thermally activated in high-density ( ≥2.9 g/cm3) tetrahedral a-C. The middle-range densities (2.4 g/cm3 ≤ρ≤ 2.9 g/cm3) are characterized by resonant tunneling and hopping transport. Our findings offer a different perspective from the tight-binding model proposed by Katkov and Bhattacharyya [J. Appl. Phys. 113, 183712 (2013)], and agree with experimental observations in low-dimensional carbon systems [see S. Bhattacharyya, Appl. Phys. Lett. 91, 21 (2007)]. Identifying transport regimes is crucial to the process of understanding and applying a-C thin film in electronic devices and electrode coating in biosensors.
Gamma Decay of Unbound Neutron-Hole States in 133Sn
Vaquero, V.; Jungclaus, A.; Doornenbal, P.; Wimmer, K.; Gargano, A.; Tostevin, J. A.; Chen, S.; Nácher, E.; Sahin, E.; Shiga, Y.; Steppenbeck, D.; Taniuchi, R.; Xu, Z. Y.; Ando, T.; Baba, H.; Garrote, F. L. Bello; Franchoo, S.; Hadynska-Klek, K.; Kusoglu, A.; Liu, J.; Lokotko, T.; Momiyama, S.; Motobayashi, T.; Nagamine, S.; Nakatsuka, N.; Niikura, M.; Orlandi, R.; Saito, T.; Sakurai, H.; Söderström, P. A.; Tveten, G. M.; Vajta, Zs.; Yalcinkaya, M.
2017-05-01
Excited states in the nucleus 133Sn, with one neutron outside the double magic 132Sn core, were populated following one-neutron knockout from a 134Sn beam on a carbon target at relativistic energies at the Radioactive Isotope Beam Factory at RIKEN. Besides the γ rays emitted in the decay of the known neutron single-particle states in 133Sn additional γ strength in the energy range 3.5-5.5 MeV was observed for the first time. Since the neutron-separation energy of 133Sn is low, Sn=2.402 (4 ) MeV , this observation provides direct evidence for the radiative decay of neutron-unbound states in this nucleus. The ability of electromagnetic decay to compete successfully with neutron emission at energies as high as 3 MeV above threshold is attributed to a mismatch between the wave functions of the initial and final states in the latter case. These findings suggest that in the region southeast of 132Sn nuclear structure effects may play a significant role in the neutron versus γ competition in the decay of unbound states. As a consequence, the common neglect of such effects in the evaluation of the neutron-emission probabilities in calculations of global β -decay properties for astrophysical simulations may have to be reconsidered.
Beltrami state in black-hole accretion disk: A magnetofluid approach
Bhattacharjee, Chinmoy; Stark, David J; Mahajan, S M
2015-01-01
Using the magnetofluid unification framework, we show that the accretion disk plasma (embedded in the background geometry of a blackhole) can relax to a class of states known as the Beltrami-Bernoulli (BB) equilibria. Modeling the disk plasma as a Hall MHD system, we find that the space-time curvature can significantly alter the magnetic/velocity decay rate as we move away from the compact object; the velocity profiles in BB states, for example, deviate substantially from the predicted corresponding geodesic velocity profiles. These departures imply a rich interplay of plasma dynamics and general relativity revealed by examining the corresponding Bernoulli condition representing "homogeneity" of total energy. The relaxed states have their origin in the constraints provided by the two helicity invariants of Hall MHD. These helicities conspire to introduce a new oscillatory length scale into the system that is strongly influenced by relativistic and thermal effects.
Kohn, W.
1983-01-01
It is shown that if n(r) is the discrete density on a lattice (enclosed in a finite box) associated with a nondegenerate ground state in an external potential v(r) (i.e., is 'v-representable'), then the density n(r) + mu(r), with m(r) arbitrary (apart from trivial constraints) and mu small enough, is also associated with a nondegenerate ground state in an external potential v'(r) near v(r); i.e., n(r) + m(r) is also v-representable. Implications for the Hohenberg-Kohn variational principle and the Kohn-Sham equations are discussed.
The density of states for an antiferromagnetic Ising model on a triangular lattice
Institute of Scientific and Technical Information of China (English)
XIA Kai; YAO Xiao-yan; LIU Jun-ming
2007-01-01
The Wang-Landau algorithm is an efficient Monte Carlo approach to the density of states of a statistical mechanics system.The estimation of state density would allow the computation of thermodynamic properties of the system over the whole temperature range.We apply this sampling method to study the phase transitions in a triangular Ising model.The entropy of the lattice at zero temperature as well as other thermodynamic properties is computed.The calculated thermodynamic properties are explained in the context of the magnetic phase transition.
THz spectroscopic investigation of chlorotoluron by solid-state density functional theory
Wang, Qiang; Wang, H. L.
2012-05-01
The terahertz time-domain spectrum (THz-TDS) of chlorotoluron has been simulated and assigned with solid-state density functional theory (DFT) in the range of 0.5-2.2 THz. The calculations based on the hybrid density functionals B3LYP and PW91 are performed to analyze the origins of observed spectral features in chlorotoluron THz spectra of solid-state forms using the software package CRYSTAL09. The computed THz spectrum of the B3LYP provides better agreements with observed THz spectral characters. Moreover, all the experimental THz absorption peaks are assigned utilizing the B3LYP method.
Density of states measurements in a p-i-n solar cell
Energy Technology Data Exchange (ETDEWEB)
Crandall, R.S.; Wang, Q. [National Renewable Energy Lab., Golden, CO (United States)
1996-05-01
The authors describe results of density of states (DOS) profiling in p-i-n solar-cell devices using drive-level capacitance (DLC) techniques. Near the p-i interface the defect density is high, decreasing rapidly into the interior, reaching low values in the central region of the cell, and rising rapidly again at the n-i interface. They show that the states in the central region are neutral dangling-bond defects, whereas those near the interfaces with the doped layers are charged dangling bonds.
Non-equilibrium steady states: fluctuations and large deviations of the density and of the current
Derrida, Bernard
2007-07-01
These lecture notes give a short review of methods such as the matrix ansatz, the additivity principle or the macroscopic fluctuation theory, developed recently in the theory of non-equilibrium phenomena. They show how these methods allow us to calculate the fluctuations and large deviations of the density and the current in non-equilibrium steady states of systems like exclusion processes. The properties of these fluctuations and large deviation functions in non-equilibrium steady states (for example, non-Gaussian fluctuations of density or non-convexity of the large deviation function which generalizes the notion of free energy) are compared with those of systems at equilibrium.
Magnetic Density of States at Low Energy in Geometrically Frustrated Systems
Yaouanc, A.; de Réotier, P. Dalmas; Glazkov, V.; Marin, C.; Bonville, P.; Hodges, J. A.; Gubbens, P. C.; Sakarya, S.; Baines, C.
2005-07-01
Using muon-spin-relaxation measurements we show that the pyrochlore compound Gd2Ti2O7, in its magnetically ordered phase below ˜1 K, displays persistent spin dynamics down to temperatures as low as 20 mK. The characteristics of the induced muon relaxation can be accounted for by a scattering process involving two magnetic excitations, with a density of states characterized by an upturn at low energy and a small gap depending linearly on the temperature. We propose that such a density of states is a generic feature of geometrically frustrated magnetic materials.
Kraisler, Eli; Argaman, Nathan; Kelson, Itzhak; 10.1103/PhysRevA.80.032115
2010-01-01
In the framework of Kohn-Sham density-functional theory, systems with ground-state densities that are not pure-state v-representable in the non-interacting reference system (PSVR) occur frequently. In the present contribution, a new algorithm, which allows the solution of such systems, is proposed. It is shown that the use of densities which do not correspond to a ground state of their non-interacting reference system is forbidden. As a consequence, the proposed algorithm considers only non-interacting ensemble v-representable densities. The Fe atom, a well-known non-PSVR system, is used as an illustration. Finally, the problem is analyzed within finite temperature density-functional theory, where the physical significance of fractional occupations is exposed and the question of why degenerate states can be unequally occupied is resolved.
Pregalactic black hole formation with an atomic hydrogen equation of state
Spaans, Marco; Silk, Joseph
2006-01-01
The polytropic equation of state of an atomic hydrogen gas is examined for primordial halos with baryonic masses of M-h similar to 10(7)-10(9) M-circle dot. For roughly isothermal collapse around 10(4) K, we find that line trapping of Ly alpha (H I and He II) photons causes the polytropic exponent t
Evolution of the phonon density of states of LaCoO3 over the spin state transition
Energy Technology Data Exchange (ETDEWEB)
Golosova, N. O. [Joint Institute for Nuclear Research, Dubna, Russia; Kozlenko, D. P. [Joint Institute for Nuclear Research, Dubna, Russia; Kolesnikov, Alexander I [ORNL; Kazimirov, V. Yu. [Joint Institute for Nuclear Research, Dubna, Russia; Smirnov, M. B. [St. Petersburg State University, St. Petersburg, Russia; Jirak, Z. [Institute of Physics, Czech Republic; Savenko, B. N. [Joint Institute for Nuclear Research, Dubna, Russia
2011-01-01
The phonon spectra of LaCoO3 were studied by inelastic neutron scattering in the temperature range of 4 120 K. The DFT calculations of the lattice dynamics have been made for interpretation of the experimental data. The observed and calculated phonon frequencies were found to be in a reasonable agreement. The evolution of the phonon density of states over the spin state transition was analyzed. In the low-temperature range (T < 50 K), an increase in the energy of resolved breathing, stretching, and bending phonon modes was found, followed by their softening and broadening at higher temperatures due to the spin state transition and relevant orbital-phonon coupling.
van Aggelen, Helen; Verstichel, Brecht; Bultinck, Patrick; Van Neck, Dimitri; Ayers, Paul W
2012-01-07
Despite the importance of non-singlet molecules in chemistry, most variational second order density matrix calculations have focused on singlet states. Ensuring that a second order density matrix is derivable from a proper N-electron spin state is a difficult problem because the second order density matrix only describes one- and two-particle interactions. In pursuit of a consistent description of spin in second order density matrix theory, we propose and evaluate two main approaches: we consider constraints derived from a pure spin state and from an ensemble of spin states. This paper makes a comparative assessment of the different approaches by applying them to potential energy surfaces for different spin states of the oxygen and carbon dimer. We observe two major shortcomings of the applied spin constraints: they are not size consistent and they do not reproduce the degeneracy of the different states in a spin multiplet. First of all, the spin constraints are less strong when applied to a dissociated molecule than when they are applied to the dissociation products separately. Although they impose correct spin expectation values on the dissociated molecule, the dissociation products do not have correct spin expectation values. Secondly, both under "pure spin state conditions" and under "ensemble spin state" conditions is the energy a convex function of the spin projection. Potential energy surfaces for different spin projections of the same spin state may give a completely different picture of the molecule's bonding. The maximal spin projection always gives the most strongly constrained energy, but is also significantly more expensive to compute than a spin-averaged ensemble. In the dissociation limit, both the problem of nondegeneracy of equivalent spin projections, size-inconsistency and unphysical dissociation can be corrected by means of subspace energy constraints.
Measuring surface state density and energy distribution in InAs nanowires
Energy Technology Data Exchange (ETDEWEB)
Halpern, Eliezer; Cohen, Gilad; Gross, Shahar; Henning, Alexander; Matok, Max; Rosenwaks, Yossi [Department of Physical Electronics, School of Electrical Engineering, Tel-Aviv University (Israel); Kretinin, Andrey V. [School of Physics and Astronomy, University of Manchester (United Kingdom); Shtrikman, Hadas [Department of Condensed Matter Physics, Braun Center for Submicrometer Research, Weizmann Institute of Science, Rehovot (Israel)
2014-02-15
Semiconducting nanowires are expected to have applications in various areas as transistors, sensors, resonators, solar cells, and thermoelectric systems. Understanding the surface properties is crucial for the fabrication of high-performance devices. Due to the large surface-to-volume ratio of nanowires, their surface electronic properties, like surface states, can a have a large effect on the performance of both electronic and optoelectronic devices. At present, determination of the surface state density depends on a combination of experimental measurements of the capacitance and/or drain current, in a nanowire field-effect transistor, and a fitting to simulation. This technique follows certain assumptions, which can severely harm the accuracy of the extracted density of states. In this report, we demonstrate a direct measurement of the surface state density of individual InAs and silicon nanowires. The method is based on measuring the surface potential of a nanowire field-effect transistor, with respect to a changing gate bias. The extracted density of states at the surface helps to explain various electronic phenomena in such devices. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Inertial blob-hole symmetry breaking in magnetised plasma filaments
Kendl, Alexander
2015-01-01
Symmetry breaking between the propagation velocities of magnetised plasma filaments with large positive (blob) and negative (hole) amplitudes, as implied by a dimensional analysis scaling, is studied with global ("full-n") non-Boussinesq gyrofluid computations, which include finite inertia effects through nonlinear polarisation. Interchange blobs on a flat density background have higher inertia and propagate more slowly than holes. In the presence of a large enough density gradient, the effect is reversed: blobs accelerate down the gradient and holes are slowed in their propagation up the gradient. Drift wave blobs spread their initial vorticity rapidly into a fully developed turbulent state, whereas primary holes can remain coherent for many eddy turnover times. The results bear implications for plasma edge zonal flow evolution and tokamak scrape-off-layer transport.
Confirming the thermal Comptonization model for black hole X-ray emission in the low-hard state
Castro, M; Braga, J; Maiolino, T; Pottschmidt, K; Wilms, J
2014-01-01
Hard X-ray spectra of black hole binaries in the low/hard state are well modeled by thermal Comptonization of soft seed photons by a corona-type region with $kT$\\thinspace$\\sim 50${\\thinspace}keV and optical depth around 1. Previous spectral studies of 1E{\\thinspace}1740.7$-$2942, including both the soft and the hard X-ray bands, were always limited by gaps in the spectra or by a combination of observations with imaging and non-imaging instruments. In this study, we have used three rare nearly-simultaneous observations of 1E{\\thinspace}1740.7$-$1942 by both XMM-Newton and INTEGRAL satellites to combine spectra from four different imaging instruments with no data gaps, and we successfully applied the Comptonization scenario to explain the broadband X-ray spectra of this source in the low/hard state. For two of the three observations, our analysis also shows that, models including Compton reflection can adequately fit the data, in agreement with previous reports. We show that the observations can also be modele...
The Hodge-elliptic genus, spinning BPS states, and black holes
Kachru, Shamit
2016-01-01
We perform a refined count of BPS states in the compactification of M-theory on $K3 \\times T^2$, keeping track of the information provided by both the $SU(2)_L$ and $SU(2)_R$ angular momenta in the $SO(4)$ little group. Mathematically, this four variable counting function may be expressed via the motivic Donaldson-Thomas counts of $K3 \\times T^2$, simultaneously refining Katz, Klemm, and Pandharipande's motivic Donaldson-Thomas counts on $K3$ and Oberdieck-Pandharipande's Gromov-Witten counts on $K3 \\times T^2$. This provides the first full answer for motivic curve counts of a compact Calabi-Yau threefold. Along the way, we develop a Hodge-elliptic genus for Calabi-Yau manifolds -- a new counting function for BPS states that interpolates between the Hodge polynomial and the elliptic genus of a Calabi-Yau.
Excited state surfaces in density functional theory: a new twist on an old problem.
Wiggins, Paul; Williams, J A Gareth; Tozer, David J
2009-09-07
Excited state surfaces in density functional theory and the problem of charge transfer are considered from an orbital overlap perspective. For common density functional approximations, the accuracy of the surface will not be uniform if the spatial overlap between the occupied and virtual orbitals involved in the excitation has a strong conformational dependence; the excited state surface will collapse toward the ground state in regions where the overlap is very low. This characteristic is used to predict and to provide insight into the breakdown of excited state surfaces in the classic push-pull 4-(dimethylamino)benzonitrile molecule, as a function of twist angle. The breakdown is eliminated using a Coulomb-attenuated functional. Analogous situations will arise in many molecules.
Semenov, S K; Titze, J; Petridis, N; Jahnke, T; Cole, K; Schmidt, L Ph H; Czasch, A; Akoury, D; Jagutzki, O; Williams, J B; Osipov, T; Lee, S; Prior, M H; Belkacem, A; Landers, A L; Schmidt-Böcking, H; Weber, Th; Cherepkov, N A; Dörner, R; 10.1103/PhysRevA.81.043426
2010-01-01
Results of the most sophisticated measurements in coincidence of the angular resolved K-shell photo- and Auger-electrons, and of two atomic ions produced by dissociation of N2 molecule, are analyzed. Detection of photoelectrons at certain angles allows separating the Auger decay processes of the 1{\\sigma}g and 1{\\sigma}u core hole states. The Auger electron angular distributions for each of these hole states are measured as a function of the kinetic energy release of two atomic ions and are compared with the corresponding theoretical angular distributions. From that comparison one can disentangle the contributions of different repulsive doubly charged molecular ion states to the Auger decay. Different kinetic energy release values are directly related to the different internuclear distances. In this way one can trace experimentally the behavior of the potential energy curves of dicationic final states inside the Frank-Condon region. Presentation of the Auger electron angular distributions as a function of kin...
Holes in Heisenberg antiferromagnets
Chen, Yang
1990-05-01
In this Brief Report we show that a recent model proposed by Shankar [Phys. Rev. Lett. 63, 203 (1989)], describing the motion of holes in quantum antiferromagnets is equivalent to the Schwinger model [Phys. Rev. 128, 2425 (1962)] in 1+1 dimensions. Some exact results are deduced. In addition to the superconducting long-range order found by Shankar, it is shown that there is a 2pF hole density wave existing with the superconducting pairing instability.
Non equilibrium steady states: fluctuations and large deviations of the density and of the current
Derrida, B.
2007-01-01
These lecture notes give a short review of methods such as the matrix ansatz, the additivity principle or the macroscopic fluctuation theory, developed recently in the theory of non-equilibrium phenomena. They show how these methods allow to calculate the fluctuations and large deviations of the density and of the current in non-equilibrium steady states of systems like exclusion processes. The properties of these fluctuations and large deviation functions in non-equilibrium steady states (fo...
Laser frequency stabilization based on steady-state spectral-hole burning in Eu$^{3+}$:Y$_2$SiO$_5$
Cook, Shon; Leibrandt, David R
2015-01-01
We present and analyze a method of laser frequency stabilization via steady-state patterns of spectral holes in Eu$^{3+}$:Y$_2$SiO$_5$. Three regions of spectral holes are created, spaced in frequency by the ground state hyperfine splittings of $~^{151}$Eu$^{3+}$. The absorption pattern is shown not to degrade after days of laser frequency stabilization. An optical frequency comparison of a laser locked to such a steady-state spectral-hole pattern with an independent cavity-stabilized laser and a Yb optical lattice clock demonstrates a spectral-hole fractional frequency instability of $1.0\\times10^{-15}~ \\tau^{-\\frac{1}{2}}$ that averages to $8.5^{+4.8}_{-1.8}\\times10^{-17}$ at $\\tau = 73$ s. Residual amplitude modulation at the frequency of the RF drive applied to the fiber-coupled electro-optic modulator is reduced to less than $1\\times10^{-6}$ fractional amplitude modulation at $\\tau>$ 1 s by an active servo. The contribution of residual amplitude modulation to the laser frequency instability is further re...
Relativistic analysis of nuclear ground state densities at 135 to 200 MeV
Indian Academy of Sciences (India)
M A Suhail; N Neeloffer; Z A Khan
2005-12-01
A relativistic analysis of p + 40Ca elastic scattering with different nuclear ground state target densities at 135 to 200 MeV is presented in this paper. It is found that the IGO densities are more consistent in reproducing the data over the energy range considered here. The reproduction of spin-rotation-function data with the simultaneous fitting of differential cross-section and analyzing power, and the appearance of wine-bottle-bottom shaped Re eff() in the transition energy region, sensitively depends on the input nuclear ground state densities and are not solely the relativistic characteristic signatures. We also found that the wine-bottle-bottom shaped Re eff() is preferred by the spin observables in the transition energy region (i.e. 181 MeV to 200 MeV).
Green's Dyadic, Spectral Function, Local Density of States, and Fluctuation Dissipation Theorem
Chew, W C; Dai, Q I
2015-01-01
The spectral functions are studied in conjunction with the dyadic Green's functions for various media. The dyadic Green's functions are found using the eigenfunction expansion method for homogeneous, inhomogeneous, periodic, lossless, lossy, and anisotropic media, guided by the Bloch- Floquet theorem. For the lossless media cases, the spectral functions can be directly related to the photon local density of states, and hence, to the electromagnetic energy density. For the lossy case, the spectral function can be related to the ?eld correlation function. Because of these properties, one can derive properties for ?eld correlations and the Langevin-source correlations without resorting to the uctuation dissipation theorem. The results are corroborated by the uctuation dissipation theorem. An expression for the local density of states for lossy, inhomogeneous, and dispersive media has also been suggested.
Restoration of density of states for FeAs-based superconductors
Kashurnikov, V. A.; Krasavin, A. V.; Zhumagulov, Ya V.
2016-09-01
The spectral and total electron density of states were calculated for two-dimensional FeAs-clusters modeling iron-based superconductors, with use of the generalized quantum Monte Carlo algorithm within the limits of the two-orbital model. The spectra have been obtained by means of the stochastic procedure, which was modified to restore the kernel of the integral equation relating the Matsubara Green's function and the spectral density. The calculations were made for clusters with sizes up to 10 × 10 FeAs-cells. The data on the total density of states near the Fermi level are obtained. There are two branches of the quasiparticle spectrum on both sides of the Fermi level. The effect of the values of the interaction parameter, the cluster size and temperature on the excitation spectra is discussed.
Electron density of states of Fe-based superconductors: Quantum trajectory Monte Carlo method
Kashurnikov, V. A.; Krasavin, A. V.; Zhumagulov, Ya. V.
2016-03-01
The spectral and total electron densities of states in two-dimensional FeAs clusters, which simulate iron-based superconductors, have been calculated using the generalized quantum Monte Carlo algorithm within the full two-orbital model. Spectra have been reconstructed by solving the integral equation relating the Matsubara Green's function and spectral density by the method combining the gradient descent and Monte Carlo algorithms. The calculations have been performed for clusters with dimensions up to 10 × 10 FeAs cells. The profiles of the Fermi surface for the entire Brillouin zone have been presented in the quasiparticle approximation. Data for the total density of states near the Fermi level have been obtained. The effect of the interaction parameter, size of the cluster, and temperature on the spectrum of excitations has been studied.
Nonequilibrium density-matrix description of steady-state quantum transport.
Dhar, Abhishek; Saito, Keiji; Hänggi, Peter
2012-01-01
With this work we investigate the stationary nonequilibrium density matrix of current carrying nonequilibrium steady states of in-between quantum systems that are connected to reservoirs. We describe the analytical procedure to obtain the explicit result for the reduced density matrix of quantum transport when the system, the connecting reservoirs, and the system-reservoir interactions are described by quadratic Hamiltonians. Our procedure is detailed for both electronic transport described by the tight-binding Hamiltonian and for phonon transport described by harmonic Hamiltonians. For the special case of weak system-reservoir couplings, a more detailed description of the steady-state density matrix is obtained. Several paradigm transport setups for interelectrode electron transport and low-dimensional phonon heat flux are elucidated.
Ludwig, Reinhold; Makarov, Sergey; Leuenberger, Georg; Apelian, Diran
2001-04-01
In this research we discuss an electrostatic measurement approach whereby electric current is injected into green-state compacts and the resulting surface voltages are recorded in an effort to determine the density distribution. We present results of pure iron powder with and without lubricants compacted to various densities and their measured electric resistivities in an effort to establish a statistical correlation. The electric measurements will ultimately be utilized to predict density distributions throughout the green-state P/M compact. The constant current is injected through point and aperture electrodes and voltages are recorded along the surface of the compact. The recorded voltages of the controlled cylindrical samples are compared to a mathematical Green's function model involving an analytical electrostatic solution of Poisson's equation.
Effective Density and Mixing State of Aerosol Particles in a Near-Traffic Urban Environment
DEFF Research Database (Denmark)
Rissler, Jenny; Nordin, Erik Z; Eriksson, Axel C
2014-01-01
-range transport from polluted continental areas. The effective density of each group was relatively stable over time, especially of the soot aggregates, which had effective densities similar to those observed in laboratory studies of fresh diesel exhaust emissions. When heated to 300 °C, the soot aggregate......In urban environments, airborne particles are continuously emitted, followed by atmospheric aging. Also, particles emitted elsewhere, transported by winds, contribute to the urban aerosol. We studied the effective density (mass-mobility relationship) and mixing state with respect to the density...... and more dense particles. Both groups were present at each size in varying proportions. Two types of temporal variability in the relative number fraction of the two groups were found: soot correlated with intense traffic in a diel pattern and dense particles increased during episodes with long...
Primitive ontology and quantum state in the GRW matter density theory
Egg, Matthias
2014-01-01
The paper explains in what sense the GRW matter density theory (GRWm) is a primitive ontology theory of quantum mechanics and why, thus conceived, the standard objections against the GRW formalism do not apply to GRWm. We consider the different options for conceiving the quantum state in GRWm and argue that dispositionalism is the most attractive one.
Alatas, Husin; Sumaryada, Tony I.; Ahmad, Faozan
2015-01-01
We have investigated the characteristics of local density of optical states (LDOS) at photonic band gap resonant wavelength of an asymmetric waveguide grating based on Green's function formulation. It is found that the LDOS of the considered structure exhibits different characteristics in its localization between the upper and lower resonant wavelengths of the corresponding photonic band gap edges.
Rendering high charge density of states in ionic liquid-gated MoS 2 transistors
Lee, Y.; Lee, J.; Kim, S.; Park, H.S.
2014-01-01
We investigated high charge density of states (DOS) in the bandgap of MoS2 nanosheets with variable temperature measurements on ionic liquid-gated MoS2 transistors. The thermally activated charge transport indicates that the electrical current in the two-dimensional MoS 2 nanosheets under high charg
Forster transfer and the local optical density of states in erbium-doped silica
de Dood, MJA; Knoester, J; Tip, A; Polman, A
2005-01-01
dOptically excited erbium ions incorporated near the surface of a silica glass decay by spontaneous emission and-at high Er concentration-via Forster energy transfer to quenching sites. By externally modifying the photonic microstructure we vary the local optical density of states (LDOS) in samples
Probing Crystallinity of Graphene Samples via the Vibrational Density of States
Jain, Sandeep K.; Juricic, Vladimir; Barkema, Gerard T.
2015-01-01
The purity of graphene samples is of crucial importance for their experimental and practical use. In this regard, the detection of the defects is of direct relevance. Here, we show that structural defects in graphene samples give rise to clear signals in the vibrational density of states (VDOS) at
DEFF Research Database (Denmark)
Johnsen, Kristinn; Yngvason, Jakob
1996-01-01
and the electron number N tend to infinity with N/Z fixed, and the magnetic field B tends to infinity in such a way that B/Z4/3→∞. We have calculated electronic density profiles and ground-state energies for values of the parameters that prevail on neutron star surfaces and compared them with results obtained...
Directory of Open Access Journals (Sweden)
V.V. Eremenko
2016-06-01
Full Text Available The electron local density of states (LDOS are calculated for graphene with isolated vacancies, divacancies and vacancy group of four nearest-neighbor vacancies. A strong anisotropy of behavior of LDOS near Fermi level is demonstrated for atoms near defect. Effect of next-to-nearest neighbor interaction on the properties of graphene with vacancies is established.
Energy Technology Data Exchange (ETDEWEB)
Rudin, A.; Aleiner, I.; Glazman, L. [Theoretical Physics Institute, University of Minnesota, Minneapolis, Minnesota 55455 (United States)
1997-01-01
We study tunneling into an interacting disordered two-dimensional electron gas in a nonquantizing magnetic field, which does not cause the standard de Haasvan Alphen oscillations. Interaction induces a new type of oscillation in the tunneling density of states with the characteristic period of cyclotron quantum {h_bar}{omega}{sub c}. {copyright} {ital 1997} {ital The American Physical Society}
Controlling fluorescent proteins by manipulating the local density of photonic states
Blum, Christian; Cesa, Yanina; Broek, van den Johanna M.; Mosk, Allard P.; Subramaniam, Vinod; Vos, Willem L.; Campagnola, Paul J.; Stelzer, Ernst H.K.; Bally, von Gert
2009-01-01
We present the first demonstration of control of the emission lifetime of a biological emitter by manipulating the local density of optical states (LDOS). LDOS control is achieved by positioning the emitters at defined distances from a metallic mirror. This results in a characteristic oscillation in
Mapping the Local Density of Optical States of a Photonic Crystal with Single Quantum Dots
DEFF Research Database (Denmark)
Wang, Qin; Stobbe, Søren; Lodahl, Peter
2011-01-01
We use single self-assembled InGaAs quantum dots as internal probes to map the local density of optical states of photonic crystal membranes. The employed technique separates contributions from nonradiative recombination and spin-flip processes by properly accounting for the role of the exciton...
Electrostatic Detection of Density Variations in Green-State Powder Metallurgy Compacts
Leuenberger, Georg; Ludwig, Reinhold
2003-03-01
Producing P/M compacts is generally a low-cost, high-volume manufacturing effort with very special quality assurance requirements. When considering the three basic P/M steps of mixing, compacting, and sintering, it is the compaction process producing the green-state parts that offer the highest pay-off for quality control through nondestructive evaluation (NDE) techniques. A detection of compacting-related problems in the green-state samples permits early process intervention, and thus prevents the creation of potentially significant numbers of faulty parts. Work at WPI currently has concentrated on extending the previously developed method for crack detections to measure density variations within the parts. In this paper a physical model and a mathematical formulation are reported that are capable of relating green-state density to electric conductivity for various lubricant concentrations. Electrostatic measurements of cylindrical compacts have so far confirmed the theoretical model assumptions. Specifically, the green-state conductivity increases as the sample density increases up to approximately 6.9 - 7.0 g/ccm. Any further density increase results in a decrease in conductivity. Preliminary measurements with a range of cylindrical samples support the theoretical model.
Energy Technology Data Exchange (ETDEWEB)
Kullie, Ossama, E-mail: kullie@uni-kassel.de [Institute de Chimie de Strasbourg, CNRS et Université de Strasbourg, Laboratoire de Chimie Quantique, 4 rue Blaise Pascal, 67070 Strasbourg (France); Theoretical Physics, Institute for Physics, Department of Mathematics and Natural Science, University of Kassel (Germany)
2013-03-29
Highlights: ► The achievement of CAMB3LYP functional for excited states in framework of TD-DFT. ► Relativistic 4-components calculations for the excited states of the Cd{sub 2} dimer. ► Relativistic Spin-Free calculations for the excited states of Cd{sub 2} dimer. ► A comparison of the achievements of different types of DFT approximations upon Cd{sub 2}. - Abstract: In this paper we present a time-dependent density functional study for the ground-state as well the 20-lowest laying excited states of the cadmium dimer Cd{sub 2}, we analyze its spectrum obtained from all electrons calculations performed with time-depended density functional for the relativistic Dirac-Coulomb- and relativistic spin-free-Hamiltonian as implemented in DIRAC-PACKAGE. The calculations were obtained with different density functional approximations, and a comparison with the literature is given as far as available. Our result is very encouraging, especially for the lowest excited states of this dimer, and is expected to be enlightened for similar systems. The result shows that only long-range corrected functionals such as CAMB3LYP, gives the correct asymptotic behavior for the higher states. A comparable but less satisfactory results were obtained with B3LYP and PBE0 functionals. Spin-free-Hamiltonian is shown to be very efficient for systems containing heavy elements such as Cd{sub 2} in frameworks of (time-dependent) density functional without introducing large errors.
Detection of X-ray spectral state transitions in mini-outbursts of black hole transient GRS 1739-278
Yan, Zhen; Yu, Wenfei
2017-10-01
We report the detection of the state transitions and hysteresis effect in the two mini-outbursts of the black hole (BH) transient GRS 1739-278 following its 2014 major outburst. The X-ray spectral evolutions in these two mini-outbursts are similar to the major outburst in spite of their peak luminosities and the outburst durations are one order of magnitude lower. We found L_hard{-to-soft} and Lpeak,soft of the mini-outbursts also follow the correlation previously found in other X-ray binaries. L_hard{-to-soft} of the mini-outbursts is still higher than that of the persistent BH binary Cyg X-1, which supports that there is a link between the maximum luminosity a source can reach in the hard state and the corresponding non-stationary accretion represented by substantial rate of change in the mass accretion rate during flares/outbursts. The detected luminosity range of these two mini-outbursts is roughly in 3.5 × 10-5 to 0.015 (D/7.5 kpc)2(M/8M⊙) LEdd. The X-ray spectra of other BH transients at such low luminosities are usually dominated by a power-law component, and an anti-correlation is observed between the photon index and the X-ray luminosity below 1 per cent LEdd. So, the detection of X-ray spectral state transitions indicates that the accretion flow evolution in these two mini-outbursts of GRS 1739-278 are different from other BH systems at such low-luminosity regime.
Proskuryakov, Y. Y.; Savchenko, A. K.; Safonov, S. S.; Pepper, M; Simmons, M.Y.; Ritchie, D. A.
2001-01-01
We examine the validity of the Fermi-liquid description of the dilute 2D hole gas in the crossover from 'metallic'-to-'insulating' behaviour of R(T).It has been established that, at r_s as large as 29, negative magnetoresistance does exist and is well described by weak localisation. The dephasing time extracted from the magnetoresistance is dominated by the T^2 -term due to Landau scattering in the clean limit. The effect of hole-hole interactions, however, is suppressed when compared with th...
Hu, Weifeng; Chan, Garnet Kin-Lic
2015-07-14
We describe and extend the formalism of state-specific analytic density matrix renormalization group (DMRG) energy gradients, first used by Liu et al. [J. Chem. Theor. Comput. 2013, 9, 4462]. We introduce a DMRG wave function maximum overlap following technique to facilitate state-specific DMRG excited-state optimization. Using DMRG configuration interaction (DMRG-CI) gradients, we relax the low-lying singlet states of a series of trans-polyenes up to C20H22. Using the relaxed excited-state geometries, as well as correlation functions, we elucidate the exciton, soliton, and bimagnon ("single-fission") character of the excited states, and find evidence for a planar conical intersection.
Govindarajan, T R
2016-01-01
Novel bound states are obtained for manifolds with singular potentials. These singular potentials require proper boundary conditions across boundaries. The number of bound states match nicely with what we would expect for black holes. Also they serve to model membrane mechanism for the black hole horizons in simpler contexts. The singular potentials can also mimic expanding boundaries elegantly, there by obtaining appropriately tuned radiation rates.
Energy Technology Data Exchange (ETDEWEB)
March, N.H
2002-12-30
The first-order density matrix {gamma}(r{sub 1},r{sub 2}) for the ground-state of a model two-electron atom is explicitly constructed from the electron density {rho}(r). The model has harmonic confinement plus interparticle harmonic interactions. {gamma}(r{sub 1},r{sub 2}) and {rho}(r) are related non-locally, even though no density gradients and no quadratures appear.
Black Hole Entropy and the Problem of Universality
Carlip, S
2008-01-01
To derive black hole thermodynamics in any quantum theory of gravity, one must introduce constraints that ensure that a black hole is actually present. For a large class of black holes, the imposition of such ``horizon constraints'' allows the use of conformal field theory methods to compute the density of states, reproducing the correct Bekenstein-Hawking entropy in a nearly model-independent manner. This approach may explain the ``universality'' of black hole entropy, the fact that many inequivalent descriptions of quantum states all seem to give the same thermodynamic predictions. It also suggests an elegant picture of the relevant degrees of freedom, as Goldstone-boson-like excitations arising from symmetry breaking by a conformal anomaly induced by the horizon constraints.
Calculating the Lifetimes of Metastable States with Complex Density Functional Theory.
Zhou, Yongxi; Ernzerhof, Matthias
2012-07-19
Among other applications, complex absorbing potentials (CAPs) have proven to be useful tools in the theory of metastable states. They facilitate the conversion of unbound states of a finite lifetime into normalized bound states with a complex energy. Adding CAPs to a conventional Hamiltonian turns it into a non-Hermitian operator. Recently, we introduced a complex density functional theory (CODFT) that extends the Kohn-Sham method to the realm of non-Hermitian systems. Here, we combine CAPs with CODFT and present the first application of CODFT to metastable systems. In particular, we consider the negative ions of the beryllium atom and the nitrogen molecule. Using conventional exchange-correlation functionals as functionals of a complex density, the resonance positions and the resonance lifetimes are obtained, and they are in line with the findings of other studies.
Phase-sensitive lock-in imaging of surface densities of states
Svec, Martin; Mutombo, Pingo; Shukrinov, Pavel; Dudr, Viktor; Cháb, Vladimír
2006-01-01
A new way of imaging the local density of states has been devised through a combination of the constant-height scanning tunnelling microscopy operational mode and lock-in techniques. We have obtained current images simultaneously with real space dynamical conductance maps (d I/d V) for energies around the Fermi level, on the Si(111)-(7 × 7) surface. We reconstructed the normalized dynamical conductance spectra—(d I/d V)/(I/V). Since the (d I/d V)/(I/V) curves are closely related to the local densities of states, we compared their sum over the unit cell to photoelectron spectra and theoretical calculations. We find that the results are in good agreement. Consequently, the extent of localization of surface electronic states at lattice positions was determined.
A dichotomy between the hard state spectral properties of black hole and neutron star X-ray binaries
Burke, M. J.; Gilfanov, M.; Sunyaev, R.
2017-04-01
We analyse the spectra of black hole (BH) and neutron star (NS) X-ray binaries (XBs) in the hard state using archival RXTE observations. We find that there is a clear dichotomy in the strength of Comptonization between NS and BH sources, as measured by both the Compton y-parameter and the amplification factor A, with distinct groups of BH and NS XBs separated at y ∼ 0.9 and A ∼ 3. The electron temperature kTe can occupy a broad range in BH systems, from kTe ∼ 30 to 200 keV, whereas for NSs kTe is peaked at ∼15-25 keV, but can extend to higher values. The difference between BHs and NSs in y implies that kTe is higher at a given optical depth for BH XBs. Our results also imply that for NS systems the accreting material loses ∼1/2-2/3 of its energy through Comptonization in the corona. The remaining energy is released on the surface of the NS, making it a powerful source of soft radiation, which alters the properties of the Comptonizing corona. Finally, we find evidence at the ∼2.4σ confidence level that Comptonization parameters may be correlated with the NS spin, whereas no correlation with the BH spin is found. Our results highlight a further observational distinction between BH and NS XBs, which is a consequence of NSs possessing a physical surface.
A dichotomy between the hard state spectral properties of black hole and neutron star X-ray binaries
Burke, M. J.; Gilfanov, M.; Sunyaev, R.
2016-10-01
We analyse the spectra of black hole (BH) and neutron star (NS) X-ray binaries (XBs) in the hard state using archival RXTE observations. We find that there is a clear dichotomy in the strength of Comptonisation between NS and BH sources, as measured by both the Compton y -parameter and amplification factor A, with distinct groups of BH and NS XBs separated at y ˜ 0.9 and A ˜ 3. The electron temperature kTe can occupy a broad range in BH systems, from kTe ˜ 30 - 200 keV, whereas for NSs kTe is peaked at ˜15 - 25 keV, but can extend to higher values. The difference between BHs and NSs in y implies that kTe is higher at a given optical depth for BH XBs. Our results also imply that for NS systems the accreting material loses ˜1/2 - 2/3 of its energy through Comptonisation in the corona. The remaining energy is released on the surface of the neutron star, making it a powerful source of soft radiation, which alters the properties of the Comptonizing corona. Finally, we find evidence at the ˜2.4σ confidence level that Comptonisation parameters may be correlated with the neutron star spin, whereas no correlation with the BH spin is found. Our results highlight a further observational distinction between BH and NS XBs that is a consequence of NSs possessing a physical surface.
A dichotomy between the hard state spectral properties of black hole and neutron star X-ray~binaries
Burke, M J; Sunyaev, R
2016-01-01
We analyse the spectra of black hole (BH) and neutron star (NS) X-ray binaries (XBs) in the hard state using archival RXTE observations. We find that there is a clear dichotomy in the strength of Comptonisation between NS and BH sources, as measured by both the Compton y-parameter and amplification factor A, with distinct groups of BH and NS XBs separated at y~0.9 and A~3. The electron temperature kTe can occupy a broad range in BH systems, from kTe~30-200 keV, whereas for NSs kTe is peaked at ~15-25 keV, but can extend to higher values. The difference between BHs and NSs in y implies that kTe is higher at a given optical depth for BH XBs. Our results also imply that for NS systems the accreting material loses ~1/2-2/3 of its energy through Comptonisation in the corona. The remaining energy is released on the surface of the neutron star, making it a powerful source of soft radiation, which alters the properties of the Comptonising corona. Finally, we find evidence at the 2.4 sigma confidence level that Compto...
Electronic and magnetic properties of spiral spin-density-wave states in transition-metal chains
Tanveer, M.; Ruiz-Díaz, P.; Pastor, G. M.
2016-09-01
The electronic and magnetic properties of one-dimensional (1D) 3 d transition-metal nanowires are investigated in the framework of density functional theory. The relative stability of collinear and noncollinear (NC) ground-state magnetic orders in V, Mn, and Fe monoatomic chains is quantified by computing the frozen-magnon dispersion relation Δ E (q ⃗) as a function of the spin-density-wave vector q ⃗. The dependence on the local environment of the atoms is analyzed by varying systematically the lattice parameter a of the chains. Electron correlation effects are explored by comparing local spin-density and generalized-gradient approximations to the exchange and correlation functional. Results are given for Δ E (q ⃗) , the local magnetic moments μ⃗i at atom i , the magnetization-vector density m ⃗(r ⃗) , and the local electronic density of states ρi σ(ɛ ) . The frozen-magnon dispersion relations are analyzed from a local perspective. Effective exchange interactions Ji j between the local magnetic moments μ⃗i and μ⃗j are derived by fitting the ab initio Δ E (q ⃗) to a classical 1D Heisenberg model. The dominant competing interactions Ji j at the origin of the NC magnetic order are identified. The interplay between the various Ji j is revealed as a function of a in the framework of the corresponding magnetic phase diagrams.
Density-dependent state-space model for population-abundance data with unequal time intervals.
Dennis, Brian; Ponciano, José Miguel
2014-08-01
The Gompertz state-space (GSS) model is a stochastic model for analyzing time-series observations of population abundances. The GSS model combines density dependence, environmental process noise, and observation error toward estimating quantities of interest in biological monitoring and population viability analysis. However, existing methods for estimating the model parameters apply only to population data with equal time intervals between observations. In the present paper, we extend the GSS model to data with unequal time intervals, by embedding it within a state-space version of the Ornstein-Uhlenbeck process, a continuous-time model of an equilibrating stochastic system. Maximum likelihood and restricted maximum likelihood calculations for the Ornstein-Uhlenbeck state-space model involve only numerical maximization of an explicit multivariate normal likelihood, and so the extension allows for easy bootstrapping, yielding confidence intervals for model parameters, statistical hypothesis testing of density dependence, and selection among sub-models using information criteria. Ecologists and managers previously drawn to models lacking density dependence or observation error because such models accommodated unequal time intervals (for example, due to missing data) now have an alternative analysis framework incorporating density dependence, process noise, and observation error.
Density dependent state space model for population abundance data with unequal time intervals
Dennis, Brian; Ponciano, José Miguel
2014-01-01
The Gompertz state-space (GSS) model is a stochastic model for analyzing time series observations of population abundances. The GSS model combines density dependence, environmental process noise, and observation error toward estimating quantities of interest in biological monitoring and population viability analysis. However, existing methods for estimating the model parameters apply only to population data with equal time intervals between observations. In the present paper, we extend the GSS model to data with unequal time intervals, by embedding it within a state-space version of the Ornstein-Uhlenbeck process, a continuous-time model of an equilibrating stochastic system. Maximum likelihood and restricted maximum likelihood calculations for the Ornstein-Uhlenbeck state-space model involve only numerical maximization of an explicit multivariate normal likelihood, and so the extension allows for easy bootstrapping, yielding confidence intervals for model parameters, statistical hypothesis testing of density dependence, and selection among sub-models using information criteria. Ecologists and managers previously drawn to models lacking density dependence or observation error because such models accommodated unequal time intervals (for example, due to missing data) now have an alternative analysis framework incorporating density dependence, process noise and observation error. PMID:25230459
Modeled Seasonal Variations of Firn Density Induced by Steady State Surface Air Temperature Cycle
Jun, Li; Zwally, H. Jay; Koblinsky, Chester J. (Technical Monitor)
2001-01-01
Seasonal variations of firn density in ice-sheet firn layers have been attributed to variations in deposition processes or other processes within the upper firn. A recent high-resolution (mm scale) density profile, measured along a 181 m core from Antarctica, showed small-scale density variations with a clear seasonal cycle that apparently was not-related to seasonal variations in deposition or known near-surface processes (Gerland and others 1999). A recent model of surface elevation changes (Zwally and Li, submitted) produced a seasonal variation in firn densification, and explained the seasonal surface elevation changes observed by satellite radar altimeters. In this study, we apply our 1-D time-dependent numerical model of firn densification that includes a temperature-dependent formulation of firn densification based on laboratory measurements of grain growth. The model is driven by a steady-state seasonal surface temperature and a constant accumulation rate appropriate for the measured Antarctic ice core. The modeled seasonal variations in firn density show that the layers of snow deposited during spring to mid-summer with the highest temperature history compress to the highest density, and the layers deposited during later summer to autumn with the lowest temperature history compress to the lowest density. The initial amplitude of the seasonal difference of about 0.13 reduces to about 0.09 in five years and asymptotically to 0.92 at depth, which is consistent with the core measurements.
Luminet, Jean-Pierre
1992-09-01
Foreword to the French edition; Foreword to the English edition; Acknowledgements; Part I. Gravitation and Light: 1. First fruits; 2. Relativity; 3. Curved space-time; Part II. Exquisite Corpses: 4. Chronicle of the twilight years; 5. Ashes and diamonds; 6. Supernovae; 7. Pulsars; 8. Gravitation triumphant; Part III. Light Assassinated: 9. The far horizon; 10. Illuminations; 11. A descent into the maelstrom; 12. Map games; 13. The black hole machine; 14. The quantum black hole; Part IV. Light Regained: 15. Primordial black holes; 16. The zoo of X-ray stars; 17. Giant black holes; 18. Gravitational light; 19. The black hole Universe; Appendices; Bibliography; Name index; Subject index.
Investigation of Spiral and Sweeping Holes
Thurman, Douglas; Poinsatte, Philip; Ameri, Ali; Culley, Dennis; Raghu, Surya; Shyam, Vikram
2015-01-01
Surface infrared thermography, hotwire anemometry, and thermocouple surveys were performed on two new film cooling hole geometries: spiral/rifled holes and fluidic sweeping holes. The spiral holes attempt to induce large-scale vorticity to the film cooling jet as it exits the hole to prevent the formation of the kidney shaped vortices commonly associated with film cooling jets. The fluidic sweeping hole uses a passive in-hole geometry to induce jet sweeping at frequencies that scale with blowing ratios. The spiral hole performance is compared to that of round holes with and without compound angles. The fluidic hole is of the diffusion class of holes and is therefore compared to a 777 hole and Square holes. A patent-pending spiral hole design showed the highest potential of the non-diffusion type hole configurations. Velocity contours and flow temperature were acquired at discreet cross-sections of the downstream flow field. The passive fluidic sweeping hole shows the most uniform cooling distribution but suffers from low span-averaged effectiveness levels due to enhanced mixing. The data was taken at a Reynolds number of 11,000 based on hole diameter and freestream velocity. Infrared thermography was taken for blowing rations of 1.0, 1.5, 2.0, and 2.5 at a density ration of 1.05. The flow inside the fluidic sweeping hole was studied using 3D unsteady RANS.
One plus two-body random matrix ensembles with parity: Density of states and parity ratios
Vyas, Manan; Srivastava, P C
2011-01-01
One plus two-body embedded Gaussian orthogonal ensemble of random matrices with parity [EGOE(1+2)-$\\pi$] generated by a chaos producing two-body interaction in the presence of a mean-field, for spinless identical fermion systems, is defined in terms of two mixing parameters and a gap between the positive $(\\pi=+)$ and negative $(\\pi=-)$ parity single particle (sp) states. Numerical calculations are used to demonstrate, using realistic values of the mixing parameters appropriate for some nuclei, that this ensemble generates Gaussian form (with corrections) for fixed parity eigenvalue densities (i.e. state densities). The random matrix model also generates many features in parity ratios of state densities that are similar to those predicted by a method based on the Fermi-gas model for nuclei. We have also obtained a simple formula for the spectral variances defined over fixed-$(m_1,m_2)$ spaces, where $m_1$ is the number of fermions in the $+$ve parity sp states and $m_2$ is the number of fermions in the $-$ve ...
Unambiguous state discrimination of two density matrices in quantum information theory
Energy Technology Data Exchange (ETDEWEB)
Raynal, P.
2008-07-01
Quantum state discrimination is a fundamental task in quantum information theory. The signals are usually nonorthogonal quantum states, which implies that they can not be perfectly distinguished. One possible discrimination strategy is the so-called Unambiguous State Discrimination (USD) where the states are successfully identified with non-unit probability, but without error. The optimal USD measurement has been extensively studied in the case of pure states, especially for any pair of pure states. Recently, the problem of unambiguously discriminating mixed quantum states has attracted much attention. In the case of a pair of generic mixed states, no complete solution is known. In this thesis, we first present reduction theorems for optimal unambiguous discrimination of two generic density matrices. We show that this problem can be reduced to that of two density matrices that have the same rank r in a 2r-dimensional Hilbert space. These reduction theorems also allow us to reduce USD problems to simpler ones for which the solution might be known. As an application, we consider the unambiguous comparison of n linearly independent pure states with a simple symmetry. Moreover, lower bounds on the optimal failure probability have been derived. For two mixed states they are given in terms of the fidelity. Here we give tighter bounds as well as necessary and sufficient conditions for two mixed states to reach these bounds. We also construct the corresponding optimal measurement. With this result, we provide analytical solutions for unambiguously discriminating a class of generic mixed states. This goes beyond known results which are all reducible to some pure state case. We however show that examples exist where the bounds cannot be reached. Next, we derive properties on the rank and the spectrum of an optimal USD measurement. This finally leads to a second class of exact solutions. Indeed we present the optimal failure probability as well as the optimal measurement for
Vacancy-induced in-gap states in sodium tungsten bronzes: Density functional investigations
Paul, S.; Kumari, S.; Raj, S.
2016-05-01
We have performed extensive ab-initio self-consistent electronic-structure calculations on WO3 and NaWO3 with single- and double-oxygen-vacancy defects within the framework of density functional theory. Our calculated density of states reveals that the in-gap states in WO3 and NaWO3 are the consequence of oxygen vacancies in the system. The evolution of the induced states occurs from the unpaired electrons donated by the oxygen vacancy. We found that the energy positions of the in-gap states are sensitive to the oxygen vacancy concentrations. The in-gap states in NaWO3 are formed close to the valence band, which are pushed towards the conduction band with the increase in oxygen vacancies, whereas the states are formed mostly in the mid-gap region in the WO3 system. Our finding can now well explain the discrepancy in experimental band dispersion measurements from ARPES with that of WO3 and NaWO3 band calculations.
A Composite Fermion Hofstadter Problem: Partially Polarized Density Wave States in the FQHE
Murthy, Ganpathy
2000-03-01
It is well known that the 2/5 FQH state can have two translationally invariant ground states, one of which is a singlet and the other fully polarized. A quantum phase transition occurs between these two as a function of the Zeeman field. This can be simply explained in terms of the crossing of Composite Fermion Landau levels. However, recently Kukushkin et al (PRL 82, 3665 (99)) have seen plateaus of half the maximal polarization in the 2/5 fraction at intermediate Zeeman fields. Similar plateaus, which are not allowed for translationally invariant CF states, are seen in other fractions as well. I propose a class of novel partially polarized spin/charge density wave states which display the co-existence of density wave and quantum Hall order (the Hall crystal state). The physical properties of the states, including gaps and collective excitations are computed using the formalism for the FQHE developed recently by Shankar and myself (for details see Murthy and Shankar in "Composite Fermions", Olle Heinonen, Editor).
Globally regular solutions of a Schwarzschild black hole and a Reissner-Nordstrom black hole
Energy Technology Data Exchange (ETDEWEB)
Shen, W.; Zhu, S.
1985-08-01
A new physical concept about globally regular solutions is suggested. The globally regular solutions corresponding to the Schwarzchild black hole and the Reissner-Nordstrom black hole are examined. The space-time metric is singularity free except for trivial coordinate singularities. Features of the metric bear some analogy with the strong interaction. The equations of state of the matter inside the Schwarzschild and the Reissner-Nordstrom black holes have the form P = -rho, where rho is the density of the matter and is independent of the carried charge; since this equation of state describes an assembly of mesons being in the relativistic dense state, does this imply that the black hole is filled with mesons. The concept of globally regular solutions does not satisfy the strong energy condition given by Hawking and Ellis (1973) and so the singularity-free behavior at r = 0 does not violate Penrose's pioneering theorem on singularities (1965). It is thought that the concept of globally regular solutions suggested will be essential to describe the geometrical and physical properties of a body and a black hole. 10 references.
Phillips, N G; Phillips, Nicholas. G.
2000-01-01
We present calculations of the variance of fluctuations and of the mean of the energy momentum tensor of a massless scalar field for the Minkowski and Casimir vacua as a function of an intrinsic scale defined by a smeared field or by point separation. We point out that contrary to prior claims, the ratio of variance to mean-squared being of the order unity is not necessarily a good criterion for measuring the invalidity of semiclassical gravity. For the Casimir topology we obtain expressions for the variance to mean-squared ratio as a function of the intrinsic scale (defined by a smeared field) compared to the extrinsic scale (defined by the separation of the plates, or the periodicity of space). Our results make it possible to identify the spatial extent where negative energy density prevails which could be useful for studying quantum field effects in worm holes and baby universe, and for examining the design feasibility of real-life `time-machines'. For the Minkowski vacuum we find that the ratio of the var...
Phillips, Nicholas G.; Hu, B. L.
2000-10-01
We present calculations of the variance of fluctuations and of the mean of the energy momentum tensor of a massless scalar field for the Minkowski and Casimir vacua as a function of an intrinsic scale defined by a smeared field or by point separation. We point out that, contrary to prior claims, the ratio of variance to mean-squared being of the order unity is not necessarily a good criterion for measuring the invalidity of semiclassical gravity. For the Casimir topology we obtain expressions for the variance to mean-squared ratio as a function of the intrinsic scale (defined by a smeared field) compared to the extrinsic scale (defined by the separation of the plates, or the periodicity of space). Our results make it possible to identify the spatial extent where negative energy density prevails which could be useful for studying quantum field effects in worm holes and baby universes, and for examining the design feasibility of real-life ``time machines.'' For the Minkowski vacuum we find that the ratio of the variance to the mean-squared, calculated from the coincidence limit, is identical to the value of the Casimir case at the same limit for spatial point separation while identical to the value of a hot flat space result with a temporal point separation. We analyze the origin of divergences in the fluctuations of the energy density and discuss choices in formulating a procedure for their removal, thus raising new questions about the uniqueness and even the very meaning of regularization of the energy momentum tensor for quantum fields in curved or even flat spacetimes when spacetime is viewed as having an extended structure.
Salen, P; Schmidt, H T; Thomas, R D; Larsson, M; Feifel, R; Piancastelli, M N; Fang, L; Murphy, B; Osipov, T; Berrah, N; Kukk, E; Ueda, K; Bozek, J D; Bostedt, C; Wada, S; Richter, R; Feyer, V; Prince, K C
2012-01-01
We have performed X-ray two-photon photoelectron spectroscopy (XTPPS) using the Linac Coherent Light Source (LCLS) X-ray free-electron laser (FEL) in order to study double core-hole (DCH) states of CO2, N2O and N2. The experiment verifies the theory behind the chemical sensitivity of two-site (ts) DCH states by comparing a set of small molecules with respect to the energy shift of the tsDCH state and by extracting the relevant parameters from this shift.
Density of states in a two-dimensional electron gas: Impurity bands and band tails
Gold, A.; Serre, J.; Ghazali, A.
1988-03-01
We calculate the density of states of a two-dimensional electron gas in the presence of charged impurities within Klauder's best multiple-scattering approach. The silicon metal-oxide-semiconductor (MOS) system with impurities at the interface is studied in detail. The finite extension of the electron wave function into the bulk is included as well as various dependences of the density of states on the electron, the depletion, and the impurity densities. The transition from an impurity band at low impurity concentration to a band tail at high impurity concentration is found to take place at a certain impurity concentration. If the screening parameter of the electron gas is decreased, the impurity band shifts to lower energy. For low impurity density we find excited impurity bands. Our theory at least qualitatively explains conductivity and infrared-absorption experiments on impurity bands in sodium-doped MOS systems and deep band tails in the gap observed for high doping levels in these systems.
Phonon structures in the electronic density of states of graphene in magnetic field
Pound, Adam; Carbotte, J. P.; Nicol, E. J.
2011-06-01
Unlike in ordinary metals, in graphene, phonon structure can be seen in the quasiparticle electronic density of states, because the latter varies on the scale of the phonon energy. In a magnetic field, quantization into Landau levels creates even more significant variations. We calculate the density of states incorporating electron-phonon coupling in this case and find that the coupling has pronounced new effects: shifting and broadening of Landau levels, creation of new peaks, and splitting of any Landau levels falling near one of the new peaks. Comparing our calculations with a recent experiment, we find evidence for a phonon with energy similar to but somewhat greater than the optical E2g mode and a coupling corresponding to a mass enhancement parameter λsime0.07.
Large-Scale Density Functional Theory Transition State Searching in Enzymes.
Lever, Greg; Cole, Daniel J; Lonsdale, Richard; Ranaghan, Kara E; Wales, David J; Mulholland, Adrian J; Skylaris, Chris-Kriton; Payne, Mike C
2014-11-06
Linear-scaling quantum mechanical density functional theory calculations have been applied to study the rearrangement of chorismate to prephenate in large-scale models of the Bacillus subtilis chorismate mutase enzyme. By treating up to 2000 atoms at a consistent quantum mechanical level of theory, we obtain an unbiased, almost parameter-free description of the transition state geometry and energetics. The activation energy barrier is calculated to be lowered by 10.5 kcal mol(-1) in the enzyme, compared with the equivalent reaction in water, which is in good agreement with experiment. Natural bond orbital analysis identifies a number of active site residues that are important for transition state stabilization in chorismate mutase. This benchmark study demonstrates that linear-scaling density functional theory techniques are capable of simulating entire enzymes at the ab initio quantum mechanical level of accuracy.
Karaveli, Sinan; Zia, Rashid
2013-01-01
We identify a solid-state quantum emitter whose room-temperature radiative decay is mediated by a nearly equal mixture of isotropic electric dipole (ED) and magnetic dipole (MD) transitions. Using energy-momentum spectroscopy, we experimentally show that the near-infrared $^3$T$_2{\\rightarrow}^3$A$_2$ emission from divalent-nickel-doped magnesium oxide (Ni$^{2+}$:MgO) is composed of $\\sim$50% MD and $\\sim$50% ED transitions. We then demonstrate that the spontaneous emission rate of these ions near planar interfaces is determined by the combined electric and magnetic local density of optical states (LDOS). This electromagnetic LDOS probes the total mode density, and thus similar to thermal emission, these unique electronic emitters effectively excite all polarizations and orientations of the electromagnetic field.
Probing the local density of states in three dimensions with a scanning single quantum emitter
Schell, Andreas W; Benson, Oliver
2013-01-01
Their intrinsic properties render single quantum systems as ideal tools for quantum enhanced sensing and microscopy. As an additional benefit, their size is typically on an atomic scale which enables sensing with very high spatial resolution. Here, we report on utilizing a single nitrogen vacancy center in nanodiamond for performing three-dimensional scanning-probe fluorescence lifetime imaging microscopy. By measuring changes of the single emitter's lifetime information on the local density of optical states is acquired at the nanoscale. This technique to gather information on the local density of optical states is important for the understanding of fundamental quantum optical processes as well as for the engineering of novel photonic and plasmonic devices.
Effects of nonlocal response on the density of states of hyperbolic metamaterials
DEFF Research Database (Denmark)
Yan, Wei; Wubs, Martijn; Mortensen, N. Asger
2012-01-01
Metamaterials with a hyperbolic dispersion curve, called hyperbolic metamaterials, exhibit an amazing broad-band singularity in the photonic density of states in the usual local-response approximation. In this paper, under the framework of the hydrodynamic Drude model, we discuss the effects...... of the nonlocal response of the electron gas in the metal on the hyperbolic metamaterials. By using mean field theory, we derive the effective material parameters of the hyperbolic metamaterials. The original unbounded hyperbolic dispersion is found to be cut off at the wavevector inverse to the Fermi velocity....... By expanding the Green function in a plane-wave basis and using the transfer matrix method to calculate the reflection coefficients, we study the local density of states (LDOS) of hyperbolic metamaterials. We show that the nonlocal response of the electron gas in the metal removes the singularity of both...
Density of states of continuous and discrete spin models: a case study
Nardini, Cesare; Nerattini, Rachele; Casetti, Lapo
2012-02-01
A relation between O(n) lattice spin models and Ising models defined on the same lattice was recently put forward (Casetti et al 2011 Phys. Rev. Lett. 106 057208). Such a relation, inspired by an energy landscape analysis, implies that the density of states of an O(n) spin model on a lattice can be effectively approximated, at least close to the phase transition, in terms of the density of states of an Ising model defined on the same lattice and with the same interactions. In this paper we show that such a relation exactly holds, albeit in a slightly modified form, in the special cases of the mean-field XY model and the one-dimensional XY model. We also discuss the possible consequences of this result for the general case.
Fermi level pinning effects at gate-dielectric interfaces influenced by interface state densities
Institute of Scientific and Technical Information of China (English)
洪文婷; 韩伟华; 吕奇峰; 王昊; 杨富华
2015-01-01
The dependences of Fermi-level pinning on interface state densities for the metal–dielectric, ploycrystalline silicon–dielectric, and metal silicide–dielectric interfaces are investigated by calculating their effective work functions and their pinning factors. The Fermi-level pinning factors and effective work functions of the metal–dielectric interface are observed to be more susceptible to the increasing interface state densities, differing significantly from that of the ploycrystalline silicon–dielectric interface and the metal silicide–dielectric interface. The calculation results indicate that metal silicide gates with high-temperature resistance and low resistivity are a more promising choice for the design of gate materials in metal-oxide semiconductor (MOS) technology.
The density number of filaments in the state of the weak and optical turbulence
Bulygin, A D
2012-01-01
We consider the statistics of density number of filaments for the propagation of a laser beam subjected to multiple filamentation in a closed area with reflecting boundaries. Dissipation arrests the catastrophic collapse of filaments, causing their disintegration into almost linear waves.These waves form a nearly gaussian random field that seeds new filaments. The evolution of the energy distribution function of the angular spectrum and accordingly law of the dynamics of formation of the thermodynamic characteristics of the light field such as the effective temperature and entropy was found. It is established that the growth rate of the thermodynamic functions and the Hamiltonian of the system grows in proportion to the number density of filaments. Also found that depending on the level of the average (background) intensity of the light field can move in two steady state. The first mode is realized for the steady state level of the background intensity does not exceed the value, and is characterized by typica...
Sub-micrometer-thick all-solid-state supercapacitors with high power and energy densities
Energy Technology Data Exchange (ETDEWEB)
Meng, Fanhui [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, and School of Chemistry and Chemical Engineering, Shandong University, Jinan 250061 (China); Ding, Yi [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, and School of Chemistry and Chemical Engineering, Shandong University, Jinan 250061 (China); Shandong Applied Research Center for Gold Technology (Au-SDARC), Yantai 264005 (China)
2011-09-15
A sub-micrometer-thick, flexible, all-solid-state supercapacitor is fabricated. Through simultaneous realization of high dispersity of pseudocapacitance materials and quick electrode response, the hybrid nanostructures show enhanced volumetric capacitance and excellent stability, as well as very high power and energy densities. This suggests their potential as next-generation, high-performance energy conversion and storage devices for wearable electronics. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Uniform existence of the integrated density of states on metric Cayley graphs
Pogorzelski, Felix; Seifert, Christian
2011-01-01
Given a finitely generated amenable group we consider ergodic random Schr\\"odinger operators on a Cayley graph with random potentials and random boundary conditions. We show that the normalised eigenvalue counting functions of finite volume parts converge uniformly. The integrated density of states as the limit can be expressed by a Pastur-Shubin formula. The spectrum supports the corresponding measure and discontinuities correspond to the existence of compactly supported eigenfunctions.
Green Function Approach to the Calculation of the Local Density of States in the Graphitic Nanocone
Directory of Open Access Journals (Sweden)
Smotlacha Jan
2016-01-01
Full Text Available Graphene and other nanostructures belong to the center of interest of today’s physics research. The local density of states of the graphitic nanocone influenced by the spin–orbit interaction was calculated. Numerical calculations and the Green function approach were used to solve this problem. It was proven in the second case that the second order approximation is not sufficient for this purpose.
Transfer Matrix Approach to 1d Random Band Matrices: Density of States
Shcherbina, Mariya; Shcherbina, Tatyana
2016-09-01
We study the special case of n× n 1D Gaussian Hermitian random band matrices, when the covariance of the elements is determined by the matrix J=(-W^2triangle +1)^{-1}. Assuming that n≥ CW log W≫ 1, we prove that the averaged density of states coincides with the Wigner semicircle law up to the correction of order W^{-1}.
Density of phonon states in the light-harvesting complex II of green plants
Pieper, J K; Irrgang, K D; Renger, G
2002-01-01
In photosynthetic antenna complexes, the coupling of electronic transitions to low-frequency vibrations of the protein matrix (phonons) plays an essential role in light absorption and ultra-fast excitation energy transfer (EET). The model calculations presented here indicate that inelastic neutron scattering experiments provide invaluable information on the phonon density of states for light-harvesting complex II, which may permit a consistent interpretation of contradictory results from high-resolution optical spectroscopy. (orig.)
Dietary vitamin C and bone mineral density in postmenopausal women in Washington State, USA.
Leveille, S.G.; LaCroix, A. Z.; Koepsell, T. D.; Beresford, S. A.; BELLE, G.; Buchner, D. M.
1997-01-01
STUDY OBJECTIVE: To examine the relationship between dietary vitamin C and hip bone mineral density (BMD) in postmenopausal women. DESIGN: This was a cross sectional study using retrospective diet and vitamin supplement data. SETTING: The Seattle area of Washington State. PARTICIPANTS: Screenees for a clinical trial of a drug to prevent osteoporotic fractures; 1892 women aged 55-80 years who had hip bone densitometry and osteoporosis risk factor information. MAIN RESULTS: Mean energy adjusted...
Nuclear single-particle states: dynamical shell model and energy density functional methods
Bortignon, P F; Sagawa, H
2010-01-01
We discuss different approaches to the problem of reproducing the observed features of nuclear single-particle (s.p.) spectra. In particular, we analyze the dominant energy peaks, and the single-particle strength fragmentation, using the example of neutron states in 208Pb. Our main emphasis is the interpretation of that fragmentation as due to particle-vibration coupling (PVC). We compare with recent Energy Density Functional (EDF) approaches, and try to present a critical perspective.
Density of states of s+d-wave superconductor with Anderson impurities
Energy Technology Data Exchange (ETDEWEB)
Borkowski, L S, E-mail: lsb@man.poznan.p [Quantum Physics Division, Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznan (Poland)
2009-03-01
We present results for the density of states of a s+d-wave superconductor containing finite concentration of Anderson impurities within the self-consistent slave boson approximation. There may be zero, one or two peaks in the energy gap at low energies. The height of the peaks is controlled by the impurity concentration whereas their position depends on the strength of interaction between impurities and the conduction band. Experimental consequences are briefly discussed.
Institute of Scientific and Technical Information of China (English)
FAN Hong-Yi; LI Chao
2004-01-01
We extend the approach of solving master equations for density matrices by projecting it onto the thermal entangled state representation (Hong-Yi Fan and Jun-Hua Chen, J. Phys. A35 (2002) 6873) to two-mode case. In this approach the two-photon master equations can be directly and conveniently converted into c-number partial differential equations. As an example, we solve the typical master equation for two-photon process in some limiting cases.
Temperature and field dependence of the mobility in 1D for a Gaussian density of states
Pasveer, W. F.; Bobbert, P. A.; Michels, M. A. J.
2004-01-01
The temperature and field-dependent mobility of a charge carrier in a gaussian density of states has been analyzed, based on a numerically exact solution of the Master equation. In this way we get a microscopic insight into the origin of the mobility and find some new features pointing to relevance of the Fermi level and of variable-range hopping to sites further away than nearest ones.
Phonon density of states in Tl 2CaBa 2Cu 2O 8
Chaplot, S. L.; Dasannacharya, B. A.; Mukhopadhyay, R.; Rao, K. R.; Vijayaraghavan, P. R.; Iyer, R. M.; Phatak, G. M.; Yakhmi, J. V.
1991-10-01
The neutron-weighted phonon density of states in the high-temperature superconductor Tl 2CaBa 2Cu 2O 8 ( Tc=107 K) is obtained from coherent inelastic neutron scattering measurements at the Dhruva reactor at 300 K. The phonon spectrum is qualitatively similar to that in the 90 K superconductor YBa 2Cu 3O 7, and compares well with an independent lattice dynamical calculation.
Non-formation of vacuum states for Navier-Stokes equations with density-dependent viscosity
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
We consider the Cauchy problem, free boundary problem and piston problem for one-dimensional compressible Navier-Stokes equations with density-dependent viscosity. Using the reduction to absurdity method, we prove that the weak solutions to these systems do not exhibit vacuum states, provided that no vacuum states are present initially. The essential requirements on the solutions are that the mass and energy of the fluid are locally integrable at each time, and the Lloc1-norm of the velocity gradient is locally integrable in time.
Landau hamiltonians with random potentials localization and the density of states
Combes, J M; Combes, J M; Hislop, P D
1994-01-01
We prove the existence of localized states at the edges of the bands for the two-dimensional Landau Hamiltonian with a random potential, of arbitrary disorder, provided that the magnetic field is sufficiently large. The corresponding eigenfunctions decay exponentially with the magnetic field and distance. We also prove that the integrated density of states is Lipschitz continuous away from the Landau energies. The proof relies on a Wegner estimate for the finite-area magnetic Hamiltonians with random potentials and exponential decay estimates for the finite-area Green's functions. The proof of the decay estimates for the Green's functions uses fundamental results from two-dimensional bond percolation theory.
Measuring the effective phonon density of states of a quantum dot in cavity quantum electrodynamics
DEFF Research Database (Denmark)
Madsen, Kristian Høeg; Nielsen, Per Kær; Kreiner-Møller, Asger
2013-01-01
We employ detuning-dependent decay-rate measurements of a quantum dot in a photonic-crystal cavity to study the influence of phonon dephasing in a solid-state quantum-electrodynamics experiment. The experimental data agree with a microscopic non-Markovian model accounting for dephasing from...... longitudinal acoustic phonons, and the analysis explains the difference between nonresonant cavity feeding in different nanocavities. From the comparison between experiment and theory we extract the effective phonon density of states experienced by the quantum dot in the nanocavity. This quantity determines...
Ergodic Properties of Local Spectral Density for a Conservative System of Coupled Quantum States
Starovoitov, V S
2002-01-01
The shape and the inverse participation ratio (IPR) of local spectral density (LSD) are studied for a generic isolated system of coupled quantum states, the Hamiltonian of which is represented by a band random matrix with the disordered leading diagonal. We find for the matrices with arbitrary small band that the lack of ergodicity for LSD can be associated with an exponential increase in IPR with the ratio $v/\\Delta_c$ ($v$ - the root of mean square for off-diagonal matrix elements, $\\Delta_c$ - the energy spacing between directly coupled basis states). Criterions specifying transition to localization and ergodicity for LSD are considered.
The evolution of the disc variability along the hard state of the black hole transient GX 339-4
De Marco, B; Muñoz-Darias, T; Nandra, K
2015-01-01
We report on the analysis of hard-state power spectral density function (PSD) of GX 339-4 down to the soft X-ray band, where the disc significantly contributes to the total emission. At any luminosity probed, the disc in the hard state is intrinsically more variable than in the soft state. However, the fast decrease of disc variability as a function of luminosity, combined with the increase of disc intensity, causes a net drop of fractional variability at high luminosities and low energies, which reminds the well-known behaviour of disc-dominated energy bands in the soft state. The peak-frequency of the high-frequency Lorentzian (likely corresponding to the high-frequency break seen in active galactic nuclei, AGN) scales with luminosity, but we do not find evidence for a linear scaling. In addition, we observe that this characteristic frequency is energy-dependent. We find that the normalization of the PSD at the peak of the high-frequency Lorentzian decreases with luminosity at all energies, though in the so...
Extraction of interface state density and resistivity of suspended p-type silicon nanobridges
Institute of Scientific and Technical Information of China (English)
Zhang Jiahong; Liu Qingquan; Ge Yixian; Gu Fang; Li Min; Mao Xiaoli; Cao Hongxia
2013-01-01
The evaluation of the influence of the bending deformation of silicon nanobridges on their electrical properties is crucial for sensing and actuating applications.A combined theory/experimental approach for determining the resistivity and the density of interface states of the bending silicon nanobridges is presented.The suspended p-type silicon nanobridge test structures were fabricated from silicon-on-insulator wafers by using a standard CMOS lithography and anisotropic wet etching release process.After that,we measured the resistance of a set of silicon nanobridges versus their length and width under different bias voltages.In conjunction with a theoretical model,we have finally extracted both the interface state density of and resistivity suspended silicon nanobridges under different bending deformations,and found that the resistivity of silicon nanobridges without bending was 9.45 mΩ·cm and the corresponding interface charge density was around 1.7445 × 1013 cm-2.The bending deformation due to the bias voltage slightly changed the resistivity of the silicon nanobridge,however,it significantly changed the distribution of interface state charges,which strongly depends on the intensity of the stress induced by bending deformation.
Nowak, Michael A; Homan, Jeroen; Yao, Yangsen; Wilms, Joern; Schulz, Norbert S; Canizares, Claude R
2008-01-01
We present simultaneous Chandra-HETG and RXTE observations of a moderate flux `soft state' of the black hole candidate 4U1957+11. These spectra, having a minimally discernible hard X-ray excess, are an excellent test of modern disk atmosphere models that include the effects of black hole spin. The HETG data show that the soft disk spectrum is only very mildly absorbed with N_H =1-2 X 10^{21} cm^-2. These data additionally reveal 13.449 A NeIX absorption consistent with the warm/hot phase of the interstellar medium. The fitted disk model implies a highly inclined disk around a low mass black hole rapidly rotating with normalized spin a*~1. We show, however, that pure Schwarzschild black hole models describe the data extremely well, albeit with large disk atmosphere ``color-correction'' factors. Standard color-correction factors can be attained if one additionally incorporates mild Comptonization. We find that the Chandra observations do not uniquely determine spin. Similarly, XMM/RXTE observations, taken only ...
Fischer, Tobias
2016-01-01
In this article the role of the supersaturation density equation of state (EOS) is explored in simulations of failed core-collapse supernova explosions. Therefore the nuclear EOS is extended via a one-parameter excluded volume description for baryons, taking into account their finite and increasing volume with increasing density in excess of saturation density. Parameters are selected such that the resulting supernova EOS represent extreme cases, with high pressure variations at supersaturation density which feature extreme stiff and soft EOS variants of the reference case, i.e. without excluded volume corrections. Unlike in the interior of neutron stars with central densities in excess of several times saturation density, central densities of core-collapse supernovae reach only slightly above saturation density. Hence, the impact of the supersaturation density EOS on the supernova dynamics as well as the neutrino signal is found to be negligible. It is mainly determined from the low- and intermediate-density...
Thermal Equation of State of Iron: Constraint on the Density Deficit of Earth's Core
Fei, Y.; Murphy, C. A.; Shibazaki, Y.; Huang, H.
2013-12-01
The seismically inferred densities of Earth's solid inner core and the liquid outer core are smaller than the measured densities of solid hcp-iron and liquid iron, respectively. The inner core density deficit is significantly smaller than the outer core density deficit, implying different amounts and/or identities of light-elements incorporated in the inner and outer cores. Accurate measurements of the thermal equation-of-state of iron over a wide pressure and temperature range are required to precisely quantify the core density deficits, which are essential for developing a quantitative composition model for the core. The challenge has been evaluating the experimental uncertainties related to the choice of pressure scales and the sample environment, such as hydrostaticity at multi-megabar pressures and extreme temperatures. We have conducted high-pressure experiments on iron in MgO, NaCl, and Ne pressure media and obtained in-situ X-ray diffraction data up to 200 GPa at room temperature. Using inter-calibrated pressure scales including the MgO, NaCl, Ne, and Pt scales, we have produced a consistent compression curve of hcp-Fe at room temperature. We have also performed laser-heated diamond-anvil cell experiments on both Fe and Pt in a Ne pressure medium. The experiment was designed to quantitatively compare the thermal expansion of Fe and Pt in the same sample environment using Ne as the pressure medium. The thermal expansion data of hcp-Fe at high pressure were derived based on the thermal equation of state of Pt. Using the 300-K isothermal compression curve of iron derived from our static experiments as a constraint, we have developed a thermal equation of state of hcp-Fe that is consistent with the static P-V-T data of iron and also reproduces the shock wave Hugoniot data for pure iron. The thermodynamic model, based on both static and dynamic data, is further used to calculate the density and bulk sound velocity of liquid iron. Our results define the solid
Shidatsu, Megumi; Nakahira, Satoshi; Negoro, Hitoshi; Yamaoka, Kazutaka; Sugizaki, Mutsumi; Hiroi, Kazuo; Kawai, Nobuyuki; Mihara, Tatehiro; Matsuoka, Masaru; Kimura, Masashi; Ishikawa, Masaki; Isobe, Naoki; Kitayama, Hiroki; Kohama, Mitsuhiro; Matsumura, Takanori; Morii, Mikio; Nakagawa, Yujin E; Nakajima, Motoki; Serino, Motoko; Sootome, Tetsuya; Sugimori, Kousuke; Suwa, Fumitoshi; Toizumi, Takahiro; Tomida, Hiroshi; Tsuboi, Yohko; Tsunemi, Hiroshi; Ueno, Shiro; Usui, Ryuichi; Yamamoto, Takayuki; Yamazaki, Kyohei; Yoshida, Atsumasa
2011-01-01
We present the results of monitoring the Galactic black hole candidate GX 339-4 with the Monitor of All-sky X-ray Image (MAXI) / Gas Slit Camera (GSC) in the high/soft state during the outburst in 2010. All the spectra throughout the 8-month period are well reproduced with a model consisting of multi-color disk (MCD) emission and its Comptonization component, whose fraction is <= 25% in the total flux. In spite of the flux variability over a factor of 3, the innermost disk radius is constant at R_in = 61 +/- 2 km for the inclination angle of i = 46 deg and the distance of d=8 kpc. This R_in value is consistent with those of the past measurements with Tenma in the high/soft state. Assuming that the disk extends to the innermost stable circular orbit of a non-spinning black hole, we estimate the black hole mass to be M = 6.8 +/- 0.2 M_sun for i = 46 deg and d = 8 kpc, which is consistent with that estimated from the Suzaku observation of the previous low/hard state. Further combined with the mass function, w...
Asymmetry of hole states in vertically coupled Ge double quantum dot%耦合锗量子点中空穴态对称特性研究
Institute of Scientific and Technical Information of China (English)
崔尉; 王茺; 崔灿; 施张胜; 杨宇
2014-01-01
The two lowest single-particle hole states in the vertically coupled Ge/Si double layer quantum dots are investigated numerically by using the single-band heavy hole effective mass approximation and six-band Kronig-Penney model, re-spectively. The calculated results indicate that within the frame of several-band coupled model, the bonding-antibonding ground-state transition and a bonding-antibonding energy anti-crossover phenomenon are observed with interdot dis-tance increasing. These results have not been observed previously in those single-band model calculations. The analysis of the wavefunction component of bonding-antibonding hole state shows that the contribution ratios of light, heavy and spin-orbital-split-off hole states to the characteristic hole wavefunction vary with the increase of the vertical coupled distance, resulting in the ground state wavefunction changing from bonding states to antibonding ones finally.%分别采用单带重空穴近似和六带Kronig-Penney模型，对垂直耦合锗量子点在不同耦合距离下的空穴态特性进行了计算，并探讨了自旋-轨道的相互作用对空穴态对称性的影响。计算结果表明：多带耦合的框架下，随着量子点垂直间距的增大，空穴基态从成键态转变为反键态，而且价带基态能级和第一激发态能级发生反交叉现象，这与单带模型下得到的相应结果存在较大差异。通过分析六带模型计算得到的成、反键态波函数，轻、重空穴态和自旋-轨道分裂态对特征空穴态波函数的贡献比例随着量子点垂直间距的增大发生了转变，并最终导致量子点空穴基态波函数由成键态转变为反键态。
Black hole geometrothermodynamics
Quevedo, Hernando
2017-03-01
We review the main aspects of geometrothermodynamics which is a geometric formalism to describe thermodynamic systems, taking into account the invariance of classical thermodynamics with respect to Legendre transformations. We focus on the particular case of black holes, and present a Riemannian metric which describes the corresponding space of equilibrium states. We show that this metric can be used to describe the stability properties and phase transition structure of black holes in different gravity theories.
Helical superconducting black holes.
Donos, Aristomenis; Gauntlett, Jerome P
2012-05-25
We construct novel static, asymptotically five-dimensional anti-de Sitter black hole solutions with Bianchi type-VII(0) symmetry that are holographically dual to superconducting phases in four spacetime dimensions with a helical p-wave order. We calculate the precise temperature dependence of the pitch of the helical order. At zero temperature the black holes have a vanishing entropy and approach domain wall solutions that reveal homogenous, nonisotropic dual ground states with an emergent scaling symmetry.
Endres, James; Egger, David A.; Kulbak, Michael; Kerner, Ross A.; Zhao, Lianfeng; Silver, Scott H.; Hodes, Gary; Rand, Barry P.; Cahen, David; Kronik, Leeor; Kahn, Antoine
2016-01-01
We report valence and conduction band densities of states measured via ultraviolet and inverse photoemission spectroscopies on three metal halide perovskites, specifically methylammonium lead iodide and bromide and cesium lead bromide (MAPbI3, MAPbBr3, CsPbBr3), grown at two different institutions on different substrates. These are compared with theoretical densities of states (DOS) calculated via density functional theory. The qualitative agreement achieved between experiment and theory lead...
A state interaction spin-orbit coupling density matrix renormalization group method
Sayfutyarova, Elvira R.; Chan, Garnet Kin-Lic
2016-06-01
We describe a state interaction spin-orbit (SISO) coupling method using density matrix renormalization group (DMRG) wavefunctions and the spin-orbit mean-field (SOMF) operator. We implement our DMRG-SISO scheme using a spin-adapted algorithm that computes transition density matrices between arbitrary matrix product states. To demonstrate the potential of the DMRG-SISO scheme we present accurate benchmark calculations for the zero-field splitting of the copper and gold atoms, comparing to earlier complete active space self-consistent-field and second-order complete active space perturbation theory results in the same basis. We also compute the effects of spin-orbit coupling on the spin-ladder of the iron-sulfur dimer complex [Fe2S2(SCH3)4]3-, determining the splitting of the lowest quartet and sextet states. We find that the magnitude of the zero-field splitting for the higher quartet and sextet states approaches a significant fraction of the Heisenberg exchange parameter.
Energy Technology Data Exchange (ETDEWEB)
Arora, Swati, E-mail: drswatia@yahoo.com [Department of Physics, Zakir Husain College, University of Delhi, Delhi 110002 (India); Singh, Vinamrita [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Arora, Manoj [Department of Physics, Ramjas College, University of Delhi, Delhi 110007 (India); Pal Tandon, Ram [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)
2012-08-01
Degradation and short shelf life have been observed experimentally in poly(3-hexylthiophene) (P3HT): 6,6-phenyl C61-butyric acid methyl ester (PCBM) based blend solar cells. Both dark and illuminated current-voltage characteristics could be explained quantitatively with a proposed single model for a typical degraded organic solar cell-glass/ITO/PEDOT:PSS/P3HT:PCBM/Al. It has been found that surface state density, interface thickness, tunneling coefficient and occupation probabilities of the interface states becomes important with the passage of time. To look into the problem the activity at ITO/PEDOT:PSS and P3HT:PCBM/Al interfaces are studied using realistic values of the interfaces. The experimental J-V characteristics is well explained with the inclusion of tunneling current through these surface states and becomes the dominant current component for the degraded cell. It is also found that surface state density increases to 10{sup 12}-10{sup 13} cm{sup -2} eV{sup -1}, which has been verified with C-V measurements and also is in agreement with our proposed model for BHJ solar cell after 150 h of fabrication.
A state interaction spin-orbit coupling density matrix renormalization group method.
Sayfutyarova, Elvira R; Chan, Garnet Kin-Lic
2016-06-21
We describe a state interaction spin-orbit (SISO) coupling method using density matrix renormalization group (DMRG) wavefunctions and the spin-orbit mean-field (SOMF) operator. We implement our DMRG-SISO scheme using a spin-adapted algorithm that computes transition density matrices between arbitrary matrix product states. To demonstrate the potential of the DMRG-SISO scheme we present accurate benchmark calculations for the zero-field splitting of the copper and gold atoms, comparing to earlier complete active space self-consistent-field and second-order complete active space perturbation theory results in the same basis. We also compute the effects of spin-orbit coupling on the spin-ladder of the iron-sulfur dimer complex [Fe2S2(SCH3)4](3-), determining the splitting of the lowest quartet and sextet states. We find that the magnitude of the zero-field splitting for the higher quartet and sextet states approaches a significant fraction of the Heisenberg exchange parameter.
Cárdenas, Carlos; Ayers, Paul W; Cedillo, Andrés
2011-05-07
Density-functional-theory-based chemical reactivity indicators are formulated for degenerate and near-degenerate ground states. For degenerate states, the functional derivatives of the energy with respect to the external potential do not exist, and must be replaced by the weaker concept of functional variation. The resultant reactivity indicators depend on the specific perturbation. Because it is sometimes impractical to compute reactivity indicators for a specific perturbation, we consider two special cases: point-charge perturbations and Dirac delta function perturbations. The Dirac delta function perturbations provide upper bounds on the chemical reactivity. Reactivity indicators using the common used "average of degenerate states approximation" for degenerate states provide a lower bound on the chemical reactivity. Unfortunately, this lower bound is often extremely weak. Approximate formulas for the reactivity indicators within the frontier-molecular-orbital approximation and special cases (two or three degenerate spatial orbitals) are presented in the supplementary material. One remarkable feature that arises in the frontier molecular orbital approximation, and presumably also in the exact theory, is that removing electrons sometimes causes the electron density to increase at the location of a negative (attractive) Dirac delta function perturbation. That is, the energetic response to a reduction in the external potential can increase even when the number of electrons decreases.
Effect of Spin on Thermodynamical Quantities around Reissner-Nordstrom Black Holes
Institute of Scientific and Technical Information of China (English)
LI Zhong-Heng
2005-01-01
@@ Using the quantization procedure involving in the Boulware vacuum state and Killing time t, we evaluate the entropy density, energy density, pressure and equation of state around the Reissner-Nordstrom black hole by the Wentzel-Kramers-Brillouin approximation on the Teukolsky-type master equation. We find that, near the event horizon, there exist subleading order terms with spin dependence beyond the expected Minkowskian hightemperature contribution. In particular, the terms are important and cannot be neglected for near-extremal black hole cases. At large r, the Boulware state approaches the Minkowski vacuum and the theory agrees with that performed in Minkowski spacetime.
A New Cosmological Model: Black Hole Universe
Directory of Open Access Journals (Sweden)
Zhang T. X.
2009-07-01
Full Text Available A new cosmological model called black hole universe is proposed. According to this model, the universe originated from a hot star-like black hole with several solar masses, and gradually grew up through a supermassive black hole with billion solar masses to the present state with hundred billion-trillion solar masses by accreting ambient mate- rials and merging with other black holes. The entire space is structured with infinite layers hierarchically. The innermost three layers are the universe that we are living, the outside called mother universe, and the inside star-like and supermassive black holes called child universes. The outermost layer is infinite in radius and limits to zero for both the mass density and absolute temperature. The relationships among all layers or universes can be connected by the universe family tree. Mathematically, the entire space can be represented as a set of all universes. A black hole universe is a subset of the en- tire space or a subspace. The child universes are null sets or empty spaces. All layers or universes are governed by the same physics - the Einstein general theory of relativity with the Robertson-walker metric of spacetime - and tend to expand outward physically. The evolution of the space structure is iterative. When one universe expands out, a new similar universe grows up from its inside. The entire life of a universe begins from the birth as a hot star-like or supermassive black hole, passes through the growth and cools down, and expands to the death with infinite large and zero mass density and absolute temperature. The black hole universe model is consistent with the Mach principle, the observations of the universe, and the Einstein general theory of relativity. Its various aspects can be understood with the well-developed physics without any difficulty. The dark energy is not required for the universe to accelerate its expansion. The inflation is not necessary because the black hole universe
Relating Follicly-Challenged Compact Stars to Bald Black Holes
Yagi, Kent
2015-01-01
Compact stars satisfy certain no-hair relations through which their multipole moments are given by their mass, spin and quadrupole moment. These relations are approximately independent of their equation of state, relating pressure to density. Such relations are similar to the black hole no-hair theorems, but these possess event horizons inside which information that led to their formation can hide. Compact stars do not possess horizons, so whether their no-hair relations are related to the black hole ones is unclear. We here show numerically that the compact star no-hair relations approach the black hole ones as the compactness approaches that of a black hole. We moreover show that compact stars become progressively oblate in this limit, even if prolate at low compactness due to strong anisotropies.
Elliptical hole in a bulk superconductor under electromagnetic forces
Energy Technology Data Exchange (ETDEWEB)
Yong Huadong; Zhou Youhe [Key Laboratory of Mechanics on Western Disaster and Environment, Ministry of Education, Lanzhou 730000 (China); Department of Mechanics, Lanzhou University, Lanzhou 730000 (China)
2009-02-15
A simple model is presented for the distribution of flux-pinning-induced stress in a superconductor around an elliptical hole and the singular stress field near crack tips. The magnetic behavior is described by the critical state, the original Bean model. It is assumed that the perturbation brought upon by the elliptical hole on the critical current density is not significant. Explicit expressions for the stress field in the vicinity of an elliptical hole are derived based on the complex variable method. Furthermore, the stress intensity factor at the tip of a slender crack is determined. An exact solution is found during the decreasing field and field-cooling process. Dependence of the stress field on the parameters including the applied field, shape of the elliptical hole or superconductor slab is investigated. The results show that the applied field and geometry parameter have obvious effects on the distribution of the stress.
Elliptical hole in a bulk superconductor under electromagnetic forces
Yong, Hua-Dong; Zhou, You-He
2009-02-01
A simple model is presented for the distribution of flux-pinning-induced stress in a superconductor around an elliptical hole and the singular stress field near crack tips. The magnetic behavior is described by the critical state, the original Bean model. It is assumed that the perturbation brought upon by the elliptical hole on the critical current density is not significant. Explicit expressions for the stress field in the vicinity of an elliptical hole are derived based on the complex variable method. Furthermore, the stress intensity factor at the tip of a slender crack is determined. An exact solution is found during the decreasing field and field-cooling process. Dependence of the stress field on the parameters including the applied field, shape of the elliptical hole or superconductor slab is investigated. The results show that the applied field and geometry parameter have obvious effects on the distribution of the stress.
DEFF Research Database (Denmark)
Zawadzki, Pawel; Rossmeisl, Jan; Jacobsen, Karsten Wedel
2011-01-01
where charge localization is strongly coupled to lattice distortion. As an example we calculate the adiabatic PES for the hole transfer process in rutile and anatase TiO2. (Semi) local DFT leads to qualitatively wrong, barrierless curves. Removal of the nonlinearity improves the PES shape and allows us...
van Sebille, M.; Vasudevan, R. A.; Lancee, R. J.; van Swaaij, R. A. C. M. M.; Zeman, M.
2015-08-01
We present a non-destructive measurement and simple analysis method for obtaining the absorption coefficient of silicon nanocrystals (NCs) embedded in an amorphous matrix. This method enables us to pinpoint the contribution of silicon NCs to the absorption spectrum of NC containing films. The density of states (DOS) of the amorphous matrix is modelled using the standard model for amorphous silicon while the NCs are modelled using one Gaussian distribution for the occupied states and one for the unoccupied states. For laser annealed a-Si0.66O0.34:H films, our analysis shows a reduction of the NC band gap from approximately 2.34-2.08 eV indicating larger mean NC size for increasing annealing laser fluences, accompanied by a reduction in NC DOS distribution width from 0.28-0.26 eV, indicating a narrower size distribution.
A new all-round density functional based on spin states and SN2 barriers
Swart, Marcel; Solà, Miquel; Bickelhaupt, F. Matthias
2009-09-01
We report here a new empirical density functional that is constructed based on the performance of OPBE and PBE for spin states and SN2 reaction barriers and how these are affected by different regions of the reduced gradient expansion. In a previous study [Swart, Solà, and Bickelhaupt, J. Comput. Methods Sci. Eng. 9, 69 (2009)] we already reported how, by switching between OPBE and PBE, one could obtain both the good performance of OPBE for spin states and reaction barriers and that of PBE for weak interactions within one and the same (SSB-sw) functional. Here we fine tuned this functional and include a portion of the KT functional and Grimme's dispersion correction to account for π-π stacking. Our new SSB-D functional is found to be a clear improvement and functions very well for biological applications (hydrogen bonding, π-π stacking, spin-state splittings, accuracy of geometries, reaction barriers).
Orthogonality of embedded wave functions for different states in frozen-density embedding theory
Energy Technology Data Exchange (ETDEWEB)
Zech, Alexander; Wesolowski, Tomasz A. [Département de Chimie Physique, Université de Genève, 30 quai Ernest-Ansermet, CH-1211 Genève 4 (Switzerland); Aquilante, Francesco [Dipartimento di Chimica “G. Ciamician,” Università di Bologna, Via Selmi 2, IT-40126 Bologna (Italy)
2015-10-28
Other than lowest-energy stationary embedded wave functions obtained in Frozen-Density Embedding Theory (FDET) [T. A. Wesolowski, Phys. Rev. A 77, 012504 (2008)] can be associated with electronic excited states but they can be mutually non-orthogonal. Although this does not violate any physical principles — embedded wave functions are only auxiliary objects used to obtain stationary densities — working with orthogonal functions has many practical advantages. In the present work, we show numerically that excitation energies obtained using conventional FDET calculations (allowing for non-orthogonality) can be obtained using embedded wave functions which are strictly orthogonal. The used method preserves the mathematical structure of FDET and self-consistency between energy, embedded wave function, and the embedding potential (they are connected through the Euler-Lagrange equations). The orthogonality is built-in through the linearization in the embedded density of the relevant components of the total energy functional. Moreover, we show formally that the differences between the expectation values of the embedded Hamiltonian are equal to the excitation energies, which is the exact result within linearized FDET. Linearized FDET is shown to be a robust approximation for a large class of reference densities.
Afek, Itai; Silberberg, Yaron
2010-01-01
We generate bipartite states of light which exhibit an absence of multiphoton coincidence events between two modes amid a constant background flux. These `correlated photon holes' are produced by mixing a coherent state and relatively weak spontaneous parametric down-conversion using a balanced beamsplitter. Correlated holes with arbitrarily high photon numbers may be obtained by adjusting the relative phase and amplitude of the inputs. We measure states of up to five photons and verify their nonclassicality. The scheme provides a route for observation of high-photon-number nonclassical correlations without requiring intense quantum resources.
Energy Technology Data Exchange (ETDEWEB)
Sirunyan, Albert M; et al.
2017-05-03
A search for new physics in energetic, high-multiplicity final states has been performed using proton-proton collision data collected with the CMS detector at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 2.3 inverse femtobarns. The standard model background, dominated by multijet production, is determined exclusively from control regions in data. No statistically significant excess of events is observed. Model-independent limits on the product of the cross section and the acceptance of a new physics signal in these final states are set and further interpreted in terms of limits on the production of black holes. Semiclassical black holes and string balls with masses as high as 9.5 TeV, and quantum black holes with masses as high as 9.0 TeV are excluded by this search in the context of models with extra dimensions, thus significantly extending limits set at a center-of-mass energy of 8 TeV with the LHC Run 1 data.
Sirunyan, Albert M; CMS Collaboration; Adam, Wolfgang; Asilar, Ece; Bergauer, Thomas; Brandstetter, Johannes; Brondolin, Erica; Dragicevic, Marko; Erö, Janos; Flechl, Martin; Friedl, Markus; Fruehwirth, Rudolf; Ghete, Vasile Mihai; Hartl, Christian; Krammer, Natascha; Hrubec, Josef; Jeitler, Manfred; König, Axel; Krätschmer, Ilse; Liko, Dietrich; Matsushita, Takashi; Mikulec, Ivan; Rabady, Dinyar; Rad, Navid; Rahbaran, Babak; Rohringer, Herbert; Schieck, Jochen; Strauss, Josef; Waltenberger, Wolfgang; Wulz, Claudia-Elisabeth; Dvornikov, Oleg; Makarenko, Vladimir; Mossolov, Vladimir; Suarez Gonzalez, Juan; Zykunov, Vladimir; Shumeiko, Nikolai; Alderweireldt, Sara; De Wolf, Eddi A; Janssen, Xavier; Lauwers, Jasper; Van De Klundert, Merijn; Van Haevermaet, Hans; Van Mechelen, Pierre; Van Remortel, Nick; Van Spilbeeck, Alex; Abu Zeid, Shimaa; Blekman, Freya; D'Hondt, Jorgen; Daci, Nadir; De Bruyn, Isabelle; Deroover, Kevin; Lowette, Steven; Moortgat, Seth; Moreels, Lieselotte; Olbrechts, Annik; Python, Quentin; Skovpen, Kirill; Tavernier, Stefaan; Van Doninck, Walter; Van Mulders, Petra; Van Parijs, Isis; Brun, Hugues; Clerbaux, Barbara; De Lentdecker, Gilles; Delannoy, Hugo; Fasanella, Giuseppe; Favart, Laurent; Goldouzian, Reza; Grebenyuk, Anastasia; Karapostoli, Georgia; Lenzi, Thomas; Léonard, Alexandre; Luetic, Jelena; Maerschalk, Thierry; Marinov, Andrey; Randle-conde, Aidan; Seva, Tomislav; Vander Velde, Catherine; Vanlaer, Pascal; Vannerom, David; Yonamine, Ryo; Zenoni, Florian; Zhang, Fengwangdong; Cimmino, Anna; Cornelis, Tom; Dobur, Didar; Fagot, Alexis; Gul, Muhammad; Khvastunov, Illia; Poyraz, Deniz; Salva Diblen, Sinem; Schöfbeck, Robert; Tytgat, Michael; Van Driessche, Ward; Yazgan, Efe; Zaganidis, Nicolas; Bakhshiansohi, Hamed; Beluffi, Camille; Bondu, Olivier; Brochet, Sébastien; Bruno, Giacomo; Caudron, Adrien; De Visscher, Simon; Delaere, Christophe; Delcourt, Martin; Francois, Brieuc; Giammanco, Andrea; Jafari, Abideh; Komm, Matthias; Krintiras, Georgios; Lemaitre, Vincent; Magitteri, Alessio; Mertens, Alexandre; Musich, Marco; Piotrzkowski, Krzysztof; Quertenmont, Loic; Selvaggi, Michele; Vidal Marono, Miguel; Wertz, Sébastien; Beliy, Nikita; Aldá Júnior, Walter Luiz; Alves, Fábio Lúcio; Alves, Gilvan; Brito, Lucas; Hensel, Carsten; Moraes, Arthur; Pol, Maria Elena; Rebello Teles, Patricia; Belchior Batista Das Chagas, Ewerton; Carvalho, Wagner; Chinellato, Jose; Custódio, Analu; Melo Da Costa, Eliza; Da Silveira, Gustavo Gil; De Jesus Damiao, Dilson; De Oliveira Martins, Carley; Fonseca De Souza, Sandro; Huertas Guativa, Lina Milena; Malbouisson, Helena; Matos Figueiredo, Diego; Mora Herrera, Clemencia; Mundim, Luiz; Nogima, Helio; Prado Da Silva, Wanda Lucia; Santoro, Alberto; Sznajder, Andre; Tonelli Manganote, Edmilson José; Torres Da Silva De Araujo, Felipe; Vilela Pereira, Antonio; Ahuja, Sudha; Bernardes, Cesar Augusto; Dogra, Sunil; Tomei, Thiago; De Moraes Gregores, Eduardo; Mercadante, Pedro G; Moon, Chang-Seong; Novaes, Sergio F; Padula, Sandra; Romero Abad, David; Ruiz Vargas, José Cupertino; Aleksandrov, Aleksandar; Hadjiiska, Roumyana; Iaydjiev, Plamen; Rodozov, Mircho; Stoykova, Stefka; Sultanov, Georgi; Shopova, Mariana; Dimitrov, Anton; Glushkov, Ivan; Litov, Leander; Pavlov, Borislav; Petkov, Peicho; Fang, Wenxing; Ahmad, Muhammad; Bian, Jian-Guo; Chen, Guo-Ming; Chen, He-Sheng; Chen, Mingshui; Chen, Ye; Cheng, Tongguang; Jiang, Chun-Hua; Leggat, Duncan; Liu, Zhenan; Romeo, Francesco; Ruan, Manqi; Shaheen, Sarmad Masood; Spiezia, Aniello; Tao, Junquan; Wang, Chunjie; Wang, Zheng; Zhang, Huaqiao; Zhao, Jingzhou; Ban, Yong; Chen, Geng; Li, Qiang; Liu, Shuai; Mao, Yajun; Qian, Si-Jin; Wang, Dayong; Xu, Zijun; Avila, Carlos; Cabrera, Andrés; Chaparro Sierra, Luisa Fernanda; Florez, Carlos; Gomez, Juan Pablo; González Hernández, Carlos Felipe; Ruiz Alvarez, José David; Sanabria, Juan Carlos; Godinovic, Nikola; Lelas, Damir; Puljak, Ivica; Ribeiro Cipriano, Pedro M; Sculac, Toni; Antunovic, Zeljko; Kovac, Marko; Brigljevic, Vuko; Ferencek, Dinko; Kadija, Kreso; Mesic, Benjamin; Susa, Tatjana; Attikis, Alexandros; Mavromanolakis, Georgios; Mousa, Jehad; Nicolaou, Charalambos; Ptochos, Fotios; Razis, Panos A; Rykaczewski, Hans; Tsiakkouri, Demetra; Finger, Miroslav; Finger Jr, Michael; Carrera Jarrin, Edgar; Assran, Yasser; Elkafrawy, Tamer; Mahrous, Ayman; Kadastik, Mario; Perrini, Lucia; Raidal, Martti; Tiko, Andres; Veelken, Christian; Eerola, Paula; Pekkanen, Juska; Voutilainen, Mikko; Härkönen, Jaakko; Jarvinen, Terhi; Karimäki, Veikko
2017-01-01
A search for new physics in energetic, high-multiplicity final states has been performed using proton-proton collision data collected with the CMS detector at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 2.3 fb$^{-1}$. The standard model background, dominated by multijet production, is determined exclusively from control regions in data. No statistically significant excess of events is observed. Model-independent limits on the product of the cross section and the acceptance of a new physics signal in these final states are set and further interpreted in terms of limits on the production of black holes. Semiclassical black holes and string balls with masses as high as 9.5 TeV, and quantum black holes with masses as high as 9.0 TeV are excluded by this search in the context of models with extra dimensions, thus significantly extending limits set at a center-of-mass energy of 8 TeV with the LHC Run 1 data.
Pikulin, D. I.; Franz, M.
2017-07-01
A system of Majorana zero modes with random infinite-range interactions—the Sachdev-Ye-Kitaev (SYK) model—is thought to exhibit an intriguing relation to the horizons of extremal black holes in two-dimensional anti-de Sitter space. This connection provides a rare example of holographic duality between a solvable quantum-mechanical model and dilaton gravity. Here, we propose a physical realization of the SYK model in a solid-state system. The proposed setup employs the Fu-Kane superconductor realized at the interface between a three-dimensional topological insulator and an ordinary superconductor. The requisite N Majorana zero modes are bound to a nanoscale hole fabricated in the superconductor that is threaded by N quanta of magnetic flux. We show that when the system is tuned to the surface neutrality point (i.e., chemical potential coincident with the Dirac point of the topological insulator surface state) and the hole has sufficiently irregular shape, the Majorana zero modes are described by the SYK Hamiltonian. We perform extensive numerical simulations to demonstrate that the system indeed exhibits physical properties expected of the SYK model, including thermodynamic quantities and two-point as well as four-point correlators, and discuss ways in which these can be observed experimentally.
Directory of Open Access Journals (Sweden)
D. I. Pikulin
2017-07-01
Full Text Available A system of Majorana zero modes with random infinite-range interactions—the Sachdev-Ye-Kitaev (SYK model—is thought to exhibit an intriguing relation to the horizons of extremal black holes in two-dimensional anti–de Sitter space. This connection provides a rare example of holographic duality between a solvable quantum-mechanical model and dilaton gravity. Here, we propose a physical realization of the SYK model in a solid-state system. The proposed setup employs the Fu-Kane superconductor realized at the interface between a three-dimensional topological insulator and an ordinary superconductor. The requisite N Majorana zero modes are bound to a nanoscale hole fabricated in the superconductor that is threaded by N quanta of magnetic flux. We show that when the system is tuned to the surface neutrality point (i.e., chemical potential coincident with the Dirac point of the topological insulator surface state and the hole has sufficiently irregular shape, the Majorana zero modes are described by the SYK Hamiltonian. We perform extensive numerical simulations to demonstrate that the system indeed exhibits physical properties expected of the SYK model, including thermodynamic quantities and two-point as well as four-point correlators, and discuss ways in which these can be observed experimentally.
Mean field theory of charge-density wave state in magnetic field
Grigoriev, Pavel; Lyubshin, Dmitrij
2005-03-01
We develop a mean field theory of charge-density wave (CDW) state in magnetic field and study properties of this state below the transition temperature. We show that the CDW state with shifted wave vector in high magnetic field (CDWx phase) has a double harmonic modulation on the most part of the phase diagram. At perfect nesting the single harmonic CDW state with shifted wave vector exists only in a very narrow region near the triple point. We show that the transition from CDW0 to CDWx state below the critical temperature is accompanied by a jump of the CDW order parameter and of the CDW wave vector rather than by their continuous increase. This implies a first order transition between these CDW states and explains a strong hysteresis accompanying this transition. The similarities between CDW in high magnetic field and nonuniform LOFF superconducting phase are pointed out. Our investigation provides a theoretical description for recent experiments on organic metal α-(BEDT-TTF)2KHg(SCN)4 and other compounds. In particular, we explain the higher value of the kink transition field and provide the calculation of the phase diagram in the case of perfect nesting.
Universal dynamics of density correlations at the transition to the many-body localized state
Mierzejewski, M.; Herbrych, J.; Prelovšek, P.
2016-12-01
Within one-dimensional disordered models of interacting fermions, we perform a numerical study of several dynamical density correlations, which can serve as hallmarks of the transition to the many-body localized state. The results confirm that density-wave correlations exhibit quite an abrupt change with increasing disorder, with a nonvanishing long-time value characteristic for the nonergodic phase. In addition, our results reveal a logarithmic variation of correlations in time in a wide time window, which we can bring in connection with the anomalous behavior of the dynamical conductivity near the transition. Our results support the view that the transition to many-body localization can be characterized by universal dynamical exponents.
Wu, Yue; Bamgbade, Babatunde A.; Burgess, Ward A.; Tapriyal, Deepak; Baled, Hseen O.; Enick, Robert M.; McHugh, Mark A.
2013-10-01
The necessity of exploring ultradeep reservoirs requires the accurate prediction of hydrocarbon density data at extreme temperatures and pressures. In this study, three equations of state (EoS) models, Peng-Robinson (PR), high-temperature high-pressure volume-translated PR (HTHP VT-PR), and perturbed-chain statistical associating fluid theory (PC-SAFT) EoS are used to predict the density data for hydrocarbons in ultradeep reservoirs at temperatures to 523 K and pressures to 275 MPa. The calculated values are compared with experimental data. The results show that the HTHP VT-PR EoS and PC-SAFT EoS always perform better than the regular PR EoS for all the investigated hydrocarbons.
Conditions for describing triplet states in reduced density matrix functional theory
Theophilou, Iris; Helbig, Nicole
2016-01-01
We consider necessary conditions for the one body-reduced density matrix (1RDM) to correspond to a triplet wave-function of a two electron system. The conditions concern the occupation numbers and are different for the high spin projections, $S_z=\\pm 1$, and the $S_z=0$ projection. We employ these conditions in reduced density matrix functional theory calculations for the triplet excitations of two electron systems. In addition, we propose that these conditions can be used in the calculation of triplet states of systems with more than two electrons by restricting the active space and assess this procedure in calculations for a few atomic and molecular systems. We show that the quality of the optimal 1RDMs improves by applying the conditions in all the cases we studied.
Low trap-state density and long carrier diffusion in organolead trihalide perovskite single crystals
Shi, Dong
2015-01-29
The fundamental properties and ultimate performance limits of organolead trihalide MAPbX3(MA = CH3NH3 +; X = Br- or I- ) perovskites remain obscured by extensive disorder in polycrystalline MAPbX3 films. We report an antisolvent vapor-assisted crystallization approach that enables us to create sizable crack-free MAPbX3 single crystals with volumes exceeding 100 cubic millimeters. These large single crystals enabled a detailed characterization of their optical and charge transport characteristics.We observed exceptionally low trap-state densities on the order of 109 to 1010 per cubic centimeter in MAPbX3 single crystals (comparable to the best photovoltaic-quality silicon) and charge carrier diffusion lengths exceeding 10 micrometers. These results were validated with density functional theory calculations.
Direct determination of defect density of states in organic bulk heterojunction solar cells
Verma, Upkar K.; Tripathi, Durgesh C.; Mohapatra, Y. N.
2016-09-01
The measurement of the occupied trap density of states (DOS) is important for optimization of organic bulk heterojunction solar cells. We demonstrate a direct method for obtaining it from the trap related peak in capacitance-voltage characteristics under different levels of illumination, and its correlation with the dark current density-voltage characteristics. We use the method to measure the parameters of DOS, occupied trap distribution, and its temperature dependence for poly(3-hexathiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM) based solar cells. The total occupied trap concentration is approximately 7 × 1015 cm-3 with a standard deviation for a truncated Gaussian distribution varying between 32 and 44 meV in the temperature range of 310-270 K within a total Gaussian DOS with a standard deviation of 92 meV.
First-principle Calculations of Equation of State for Metals at High Energy Density
Minakov, Dmitry; Levashov, Pavel; Khishchenko, Konstantin
2012-02-01
In this work, we present quantum molecular dynamics calculations of the shock Hugoniots of solid and porous samples as well as release isentropes and isentropic sound velocity behind the shock front for aluminum. Also we perform similar calculations for nickel and iron. We use the VASP code with ultrasoft and PAW pseudopotentials and GGA exchange-correlation functional. Up to 512 particles have been used in calculations. To calculate Hugoniots we solve the Hugoniot equation numerically. To obtain release isentropes, we use Zel'dovich's approach and integrate an ordinary differential equation for the temperature thus restoring all thermodynamic parameters. Isentropic sound velocity is calculated by differentiation of pressure along isentropes. The results of our calculations are in good agreement with experimental data at densities both higher and lower than the normal one. Thus, quantum molecular dynamics results can be effectively used for verification or calibration of semiempirical equations of state under conditions of lack of experimental information at high energy densities.
Semilocal and Hybrid Density Embedding Calculations of Ground-State Charge-Transfer Complexes
Laricchia, S; Della Sala, F; 10.1063/1.4795825
2013-01-01
We apply the frozen density embedding method, using a full relaxation of embedded densities through a freeze-and-thaw procedure, to study the electronic structure of several benchmark ground-state charge-transfer complexes, in order to assess the merits and limitations of the approach for this class of systems. The calculations are performed using both semilocal and hybrid exchange-correlation (XC) functionals. The results show that embedding calculations using semilocal XC functionals yield rather large deviations with respect to the corresponding supermolecular calculations. Due to a large error cancellation effect, however, they can often provide a relatively good description of the electronic structure of charge-transfer complexes, in contrast to supermolecular calculations performed at the same level of theory. On the contrary, when hybrid XC functionals are employed, both embedding and supermolecular calculations agree very well with each other and with the reference benchmark results. In conclusion, fo...
Aad, Georges; Abbott, Brad; Abdallah, Jalal; Abdel Khalek, Samah; Abdinov, Ovsat; Aben, Rosemarie; Abi, Babak; Abolins, Maris; AbouZeid, Ossama; Abramowicz, Halina; Abreu, Henso; Abulaiti, Yiming; Acharya, Bobby Samir; Adamczyk, Leszek; Adams, David; Addy, Tetteh; Adelman, Jahred; Adomeit, Stefanie; Adye, Tim; Aefsky, Scott; Agatonovic-Jovin, Tatjana; Aguilar-Saavedra, Juan Antonio; Agustoni, Marco; Ahlen, Steven; Ahmad, Ashfaq; Ahmadov, Faig; Ahsan, Mahsana; Aielli, Giulio; Åkesson, Torsten Paul Ake; Akimoto, Ginga; Akimov, Andrei; Alam, Muhammad Aftab; Albert, Justin; Albrand, Solveig; Alconada Verzini, Maria Josefina; Aleksa, Martin; Aleksandrov, Igor; Alessandria, Franco; Alexa, Calin; Alexander, Gideon; Alexandre, Gauthier; Alexopoulos, Theodoros; Alhroob, Muhammad; Aliev, Malik; Alimonti, Gianluca; Alio, Lion; Alison, John; Allbrooke, Benedict; Allison, Lee John; Allport, Phillip; Allwood-Spiers, Sarah; Almond, John; Aloisio, Alberto; Alon, Raz; Alonso, Alejandro; Alonso, Francisco; Altheimer, Andrew David; Alvarez Gonzalez, Barbara; Alviggi, Mariagrazia; Amako, Katsuya; Amaral Coutinho, Yara; Amelung, Christoph; Ammosov, Vladimir; Amor Dos Santos, Susana Patricia; Amorim, Antonio; Amoroso, Simone; Amram, Nir; Anastopoulos, Christos; Ancu, Lucian Stefan; Andari, Nansi; Andeen, Timothy; Anders, Christoph Falk; Anders, Gabriel; Anderson, Kelby; Andreazza, Attilio; Andrei, George Victor; Anduaga, Xabier; Angelidakis, Stylianos; Anger, Philipp; Angerami, Aaron; Anghinolfi, Francis; Anisenkov, Alexey; Anjos, Nuno; Annovi, Alberto; Antonaki, Ariadni; Antonelli, Mario; Antonov, Alexey; Antos, Jaroslav; Anulli, Fabio; Aoki, Masato; Aperio Bella, Ludovica; Apolle, Rudi; Arabidze, Giorgi; Aracena, Ignacio; Arai, Yasuo; Arce, Ayana; Arfaoui, Samir; Arguin, Jean-Francois; Argyropoulos, Spyridon; Arik, Engin; Arik, Metin; Armbruster, Aaron James; Arnaez, Olivier; Arnal, Vanessa; Arslan, Ozan; Artamonov, Andrei; Artoni, Giacomo; Asai, Shoji; Asbah, Nedaa; Ask, Stefan; Åsman, Barbro; Asquith, Lily; Assamagan, Ketevi; Astalos, Robert; Astbury, Alan; Atkinson, Markus; Atlay, Naim Bora; Auerbach, Benjamin; Auge, Etienne; Augsten, Kamil; Aurousseau, Mathieu; Avolio, Giuseppe; Axen, David; Azuelos, Georges; Azuma, Yuya; Baak, Max; Bacci, Cesare; Bach, Andre; Bachacou, Henri; Bachas, Konstantinos; Backes, Moritz; Backhaus, Malte; Backus Mayes, John; Badescu, Elisabeta; Bagiacchi, Paolo; Bagnaia, Paolo; Bai, Yu; Bailey, David; Bain, Travis; Baines, John; Baker, Oliver Keith; Baker, Sarah; Balek, Petr; Balli, Fabrice; Banas, Elzbieta; Banerjee, Swagato; Banfi, Danilo; Bangert, Andrea Michelle; Bansal, Vikas; Bansil, Hardeep Singh; Barak, Liron; Baranov, Sergei; Barber, Tom; Barberio, Elisabetta Luigia; Barberis, Dario; Barbero, Marlon; Bardin, Dmitri; Barillari, Teresa; Barisonzi, Marcello; Barklow, Timothy; Barlow, Nick; Barnett, Bruce; Barnett, Michael; Baroncelli, Antonio; Barone, Gaetano; Barr, Alan; Barreiro, Fernando; Barreiro Guimarães da Costa, João; Bartoldus, Rainer; Barton, Adam Edward; Bartsch, Valeria; Bassalat, Ahmed; Basye, Austin; Bates, Richard; Batkova, Lucia; Batley, Richard; Battistin, Michele; Bauer, Florian; Bawa, Harinder Singh; Beale, Steven; Beau, Tristan; Beauchemin, Pierre-Hugues; Beccherle, Roberto; Bechtle, Philip; Beck, Hans Peter; Becker, Anne Kathrin; Becker, Sebastian; Beckingham, Matthew; Beddall, Andrew; Beddall, Ayda; Bedikian, Sourpouhi; Bednyakov, Vadim; Bee, Christopher; Beemster, Lars; Beermann, Thomas; Begel, Michael; Belanger-Champagne, Camille; Bell, Paul; Bell, William; Bella, Gideon; Bellagamba, Lorenzo; Bellerive, Alain; Bellomo, Massimiliano; Belloni, Alberto; Beloborodova, Olga; Belotskiy, Konstantin; Beltramello, Olga; Benary, Odette; Benchekroun, Driss; Bendtz, Katarina; Benekos, Nektarios; Benhammou, Yan; Benhar Noccioli, Eleonora; Benitez Garcia, Jorge-Armando; Benjamin, Douglas; Bensinger, James; Benslama, Kamal; Bentvelsen, Stan; Berge, David; Bergeaas Kuutmann, Elin; Berger, Nicolas; Berghaus, Frank; Berglund, Elina; Beringer, Jürg; Bernard, Clare; Bernat, Pauline; Bernhard, Ralf; Bernius, Catrin; Bernlochner, Florian Urs; Berry, Tracey; Berta, Peter; Bertella, Claudia; Bertolucci, Federico; Besana, Maria Ilaria; Besjes, Geert-Jan; Bessidskaia, Olga; Besson, Nathalie; Bethke, Siegfried; Bhimji, Wahid; Bianchi, Riccardo-Maria; Bianchini, Louis; Bianco, Michele; Biebel, Otmar; Bieniek, Stephen Paul; Bierwagen, Katharina; Biesiada, Jed; Biglietti, Michela; Bilbao De Mendizabal, Javier; Bilokon, Halina; Bindi, Marcello; Binet, Sebastien; Bingul, Ahmet; Bini, Cesare
2013-01-01
A search for microscopic black holes in a like-sign dimuon final state in proton−proton collisions at √s = 8 TeV is presented. The data were collected with the ATLAS detector at the Large Hadron Collider in 2012 and correspond to an integrated luminosity of 20.3 fb$^{-1}$. Using a high track multiplicity requirement, 0.6 $\\pm$ 0.2 background events are predicted from Standard Model processes and none are observed. This result is interpreted in the context of low-scale gravity models and 95% CL lower limits on microscopic black hole masses are set at 3.7 TeV through 5.9 TeV depending on the model assumptions.
Directory of Open Access Journals (Sweden)
Arifa Jamil
2016-05-01
Full Text Available Temperature and frequency dependent ac electrical measurements were used to explore density of states, conduction mechanisms and dielectric properties of nickel disulfide (NiS2 nanoparticles. The NiS2 nanoparticles were prepared by conventional one step solid state reaction method at 250 °C. X-ray diffraction (XRD confirmed cubic phase of prepared nanoparticles. Scanning electron microscope (SEM images revealed presence of irregular shaped nanoparticles as small as 50 nm. The ac electrical measurements were carried out from 300 K to 413 K. Two depressed semicircular arcs from 20 Hz to 2 MHz showed presence of bulk and grain boundary phases in NiS2 nanoparticles at all temperatures. Small polaron hopping conduction from 300 K to 393 K and correlated barrier hopping conduction mechanism at temperatures higher than 393 K was observed. High value of density of states (of the order of 1024 eV−1cm−3 was calculated from ac conductivity. At low frequencies high values (of the order of 104-107 of real part of dielectric constant (ε′ were observed at different temperatures. These observations suggest that NiS2 nanoparticles may find applications in electronic devices.
Do Spin State and Spin Density Affect Hydrogen Atom Transfer Reactivity?
Saouma, Caroline T; Mayer, James M
2014-01-01
The prevalence of hydrogen atom transfer (HAT) reactions in chemical and biological systems has prompted much interest in establishing and understanding the underlying factors that enable this reactivity. Arguments have been advanced that the electronic spin state of the abstractor and/or the spin-density at the abstracting atom are critical for HAT reactivity. This is consistent with the intuition derived from introductory organic chemistry courses. Herein we present an alternative view on the role of spin state and spin-density in HAT reactions. After a brief introduction, the second section introduces a new and simple fundamental kinetic analysis, which shows that unpaired spin cannot be the dominant effect. The third section examines published computational studies of HAT reactions, which indicates that the spin state affects these reactions indirectly, primarily via changes in driving force. The essay concludes with a broader view of HAT reactivity, including indirect effects of spin and other properties on reactivity. It is suggested that some of the controversy in this area may arise from the diversity of HAT reactions and their overlap with proton-coupled electron transfer (PCET) reactions.
A relativistic time-dependent density functional study of the excited states of the mercury dimer
Energy Technology Data Exchange (ETDEWEB)
Kullie, Ossama, E-mail: kullie@uni-kassel.de, E-mail: ossama.kullie@unistra.fr [Institute de Chimie de Strasbourg, CNRS et Université de Strasbourg, Laboratoire de Chimie Quantique, 4 rue Blaise Pascal, 67070 Strasbourg, France and Theoretical Physics, Institute for Physics, Department of Mathematics and Natural Science, University of Kassel, D-34127 Kassel (Germany)
2014-01-14
In previous works on Zn{sub 2} and Cd{sub 2} dimers we found that the long-range corrected CAMB3LYP gives better results than other density functional approximations for the excited states, especially in the asymptotic region. In this paper, we use it to present a time-dependent density functional (TDDFT) study for the ground-state as well as the excited states corresponding to the (6s{sup 2} + 6s6p), (6s{sup 2} + 6s7s), and (6s{sup 2} + 6s7p) atomic asymptotes for the mercury dimer Hg{sub 2}. We analyze its spectrum obtained from all-electron calculations performed with the relativistic Dirac-Coulomb and relativistic spinfree Hamiltonian as implemented in DIRAC-PACKAGE. A comparison with the literature is given as far as available. Our result is excellent for the most of the lower excited states and very encouraging for the higher excited states, it shows generally good agreements with experimental results and outperforms other theoretical results. This enables us to give a detailed analysis of the spectrum of the Hg{sub 2} including a comparative analysis with the lighter dimers of the group 12, Cd{sub 2}, and Zn{sub 2}, especially for the relativistic effects, the spin-orbit interaction, and the performance of CAMB3LYP and is enlightened for similar systems. The result shows, as expected, that spinfree Hamiltonian is less efficient than Dirac-Coulomb Hamiltonian for systems containing heavy elements such as Hg{sub 2}.
An efficient algorithm for numerical computations of continuous densities of states
Langfeld, K.; Lucini, B.; Pellegrini, R.; Rago, A.
2016-06-01
In Wang-Landau type algorithms, Monte-Carlo updates are performed with respect to the density of states, which is iteratively refined during simulations. The partition function and thermodynamic observables are then obtained by standard integration. In this work, our recently introduced method in this class (the LLR approach) is analysed and further developed. Our approach is a histogram free method particularly suited for systems with continuous degrees of freedom giving rise to a continuum density of states, as it is commonly found in lattice gauge theories and in some statistical mechanics systems. We show that the method possesses an exponential error suppression that allows us to estimate the density of states over several orders of magnitude with nearly constant relative precision. We explain how ergodicity issues can be avoided and how expectation values of arbitrary observables can be obtained within this framework. We then demonstrate the method using compact U(1) lattice gauge theory as a show case. A thorough study of the algorithm parameter dependence of the results is performed and compared with the analytically expected behaviour. We obtain high precision values for the critical coupling for the phase transition and for the peak value of the specific heat for lattice sizes ranging from 8^4 to 20^4. Our results perfectly agree with the reference values reported in the literature, which covers lattice sizes up to 18^4. Robust results for the 20^4 volume are obtained for the first time. This latter investigation, which, due to strong metastabilities developed at the pseudo-critical coupling of the system, so far has been out of reach even on supercomputers with importance sampling approaches, has been performed to high accuracy with modest computational resources. This shows the potential of the method for studies of first order phase transitions. Other situations where the method is expected to be superior to importance sampling techniques are pointed
An efficient algorithm for numerical computations of continuous densities of states
Energy Technology Data Exchange (ETDEWEB)
Langfeld, K.; Rago, A. [Plymouth University, Centre for Mathematical Sciences, Plymouth (United Kingdom); Lucini, B. [Swansea University, College of Science, Swansea (United Kingdom); Pellegrini, R. [University of Edinburgh, School of Physics and Astronomy, Edinburgh (United Kingdom)
2016-06-15
In Wang-Landau type algorithms, Monte-Carlo updates are performed with respect to the density of states, which is iteratively refined during simulations. The partition function and thermodynamic observables are then obtained by standard integration. In this work, our recently introduced method in this class (the LLR approach) is analysed and further developed. Our approach is a histogram free method particularly suited for systems with continuous degrees of freedom giving rise to a continuum density of states, as it is commonly found in lattice gauge theories and in some statistical mechanics systems. We show that the method possesses an exponential error suppression that allows us to estimate the density of states over several orders of magnitude with nearly constant relative precision. We explain how ergodicity issues can be avoided and how expectation values of arbitrary observables can be obtained within this framework. We then demonstrate the method using compact U(1) lattice gauge theory as a show case. A thorough study of the algorithm parameter dependence of the results is performed and compared with the analytically expected behaviour. We obtain high precision values for the critical coupling for the phase transition and for the peak value of the specific heat for lattice sizes ranging from 8{sup 4} to 20{sup 4}. Our results perfectly agree with the reference values reported in the literature, which covers lattice sizes up to 18{sup 4}. Robust results for the 20{sup 4} volume are obtained for the first time. This latter investigation, which, due to strong metastabilities developed at the pseudo-critical coupling of the system, so far has been out of reach even on supercomputers with importance sampling approaches, has been performed to high accuracy with modest computational resources. This shows the potential of the method for studies of first order phase transitions. Other situations where the method is expected to be superior to importance sampling
The information entropy of a static dilaton black hole
Institute of Scientific and Technical Information of China (English)
LIU ChengZhou
2008-01-01
In accordance with holographic principle, by calculating the statistical entropy of the quantum field just at the event horizon of the Garfinkle-Horowitz-Strominger dilaton black hole, the information entropy of the black hole was investigated and the Bekenstein-Hawking formula was obtained. The results show that black hole entropy is identical with the statistical entropy of the quantum field at the horizon. Using the generalized uncertainty relation, the divergence of the state density near the event horizon in usual quantum field theory was removed, and the cutoffs and the little mass approximation in the heat gas method of black hole entropy were avoided. Thus, the microstates of the massive scalar field just at the event horizon of the static dilaton black hole were studied directly and a description on holograph principle was presented. By using residue theorem, the integral difficulty in the calculation was overcome, and the information entropy and the Bekenstein-Hawking formula were obtained quantitatively. Compared with the black hole entropy from the loop quantum gravity, the consistency of methods and results of calculating black hole entropy in non-commutative quantum field theory and loop quantum gravity was investigated. By this, the gravity correction constant in the generalized uncertainty relation was suggested and the sense of holographic principle was discussed.
On the change of density of states in two-body interactions
Gao, Bo
2016-01-01
We derive a general relation in two-body scattering theory that more directly relates the change of density of states (DDOS) due to interaction to the shape of the potential. The relation allows us to infer certain global properties of the DDOS from the global properties of the potential. In particular, we show that DDOS is negative at all energies and for all partial waves, for potentials that are more repulsive than $+1/r^2$ everywhere. This behavior represents a different class of global properties of DDOS from that described by the Levinson's theorem.
Density of states controls Anderson localization in disordered photonic crystal waveguides
DEFF Research Database (Denmark)
Garcia-Fernández, David; Smolka, Stephan; Stobbe, Søren
2010-01-01
-of-plane losses are non-negligible, ℓe can be approximated to be the localization length ξ. The extinction mean-free path shows a fivefold variation between the low- and the high-DOS regime, and it becomes shorter than the sample length thus giving rise to strongly confined modes. The dispersive behavior of ℓe......We prove Anderson localization in a disordered photonic crystal waveguide by measuring the ensemble-averaged extinction mean-free path, ℓe, which is controlled by the dispersion in the photon density of states (DOS) of the photonic crystal waveguide. Except for the very low DOS case, where out...
Noh, Han-Jin; Nahm, Tschang-Uh; Kim, Jae-Young; Park, W.-G.; Oh, S.-J.; Hong, J.-P.; Kim, C.-O.
2000-03-01
We have performed high resolution photoemission study of substitutionally disordered alloys Cu-Pt, Cu-Pd, Cu-Ni, and Pd-Pt. The ratios between alloy spectra and pure metal spectra are found to have dips at the Fermi level when the residual resistivity is high and when rather strong repulsive electron-electron interaction is expected. This is in accordance with Altshuler and Aronov's model which predicts depletion of density of states at the Fermi level when both disorder and electron correlation are present.
Tracing the equation of state and the density of the cosmological constant along z
Energy Technology Data Exchange (ETDEWEB)
Espana-Bonet, Cristina; Ruiz-Lapuente, Pilar, E-mail: cespana@am.ub.es, E-mail: pilar@am.ub.es [Departament of Astronomy, University of Barcelona, CER en Astrofisica, Fisica de Particules i Cosmologia i, Institut de Ciencies del Cosmos, Universitat de Barcelona ICCUB, Diagonal 647, Barcelona E-08028 (Spain)
2008-02-15
We investigate the equation of state w(z) in a non-parametric form using the latest compilations of the luminosity distance from SNe Ia at high z. We combine the inverse problem approach with a Monte Carlo method to scan the space of priors. In the light of the latest high redshift supernova data sets, we reconstruct w(z). A comparison between a sample including the latest results at z>1 and a sample without those results shows the improvement achieved through observations of very high z supernovae. We present the prospects for measuring the variation of dark energy density along z by this method.
Imaging of 5f densities of states in resonant photoemission measurements
Energy Technology Data Exchange (ETDEWEB)
Arko, A.J.; Koelling, D.D.; Capasso, C.; del Giudice, M.; Olson, C.G.
1988-07-15
Medium-resolution spectra (..delta..E = 0.25 eV) at the 5f Fano resonance in uranium intermetallics are compared to spectra above and below the resonance region to show that the 5f (and 6d) spectral weight obtained from resonant photoemission (RP) compares well to the 5f spectral weight obtained at other photon energies. In well-hybridized systems, the 5f signal from RP gives an excellent representation of the 5f density of states (DOS). In narrow-band and localized systems, a satellite may appear in addition to 5f DOS-like structure, indicative of correlation effects.
Comparing the density of states of binary Lennard-Jones glasses in bulk and film
Ghosh, Jayeeta; Faller, Roland
2008-03-01
We used Wang-Landau density of states Monte Carlo to study a binary Lennard-Jones glass-forming mixture in bulk and films between noninteracting walls. Thermodynamic properties are calculated using two different ensembles and film data are compared with the bulk. Bulk properties are in good agreement with previous simulations. We confirm the formation of a glass using various properties, e.g., energy, heat capacity, and pressure with temperature. We find a change in slope in the energy per particle and pressure as a function of temperature. We do not find any defined crystal structure. A higher glass transition temperature is found for the film.
Observation of spatial fluctuations of the local density of states in random photonic media.
Birowosuto, M D; Skipetrov, S E; Vos, W L; Mosk, A P
2010-07-02
We experimentally study spatial fluctuations of the local density of states (LDOS) inside three-dimensional random photonic media. The LDOS is probed at many positions inside random photonic media by measuring emission rates of a large number of individual fluorescent nanospheres. The emission rates are observed to fluctuate spatially, and the variance of the fluctuations increases with the scattering strength. The measured variance of the emission rates agrees well with a model that takes into account the effect of the nearest scatterer only.
Plastic flow rule for sands with friction, dilation, density and stress state coupling
Directory of Open Access Journals (Sweden)
Wojciechowski Marek
2015-06-01
Full Text Available In this paper we propose a flow rule and failure criterion for sands in plane strain conditions based on Drucker-Prager formulation and enhanced with empirical Houlsby formula, which couples friction, dilation, density and stress state in the material. The resulting elasto-plastic, non-associated, shear hardening material model is implemented as a numerical procedure in the frame of finite element method and a simple compression example is presented. Because of the empirical nature of Houlsby formula, it is believed that results of numerical simulations will be more realistic both in deformation and shear strength estimation of sands.
Role of Optical Density of States in Two-mode Optomechanical Cooling
Kim, Seunghwi
2016-01-01
Dynamical back-action cooling of phonons in optomechanical systems having one optical mode is well studied. Systems with two optical modes have the potential to reach significantly higher cooling rate through resonant enhancement of both pump and scattered light. Here we experimentally investigate the role of dual optical densities of states on optomechanical cooling, and the deviation from theory caused by thermal locking to the pump laser. Using this, we demonstrate a room temperature system operating very close to the strong coupling regime, where saturation of cooling is anticipated.
Tracing the equation of state and the density of cosmological constant along z
Espana-Bonet, Cristina
2008-01-01
We investigate the equation of state w(z) in a non-parametric form using the latest compilations of distance luminosity from SNe Ia at high z. We combine the inverse problem approach with a Monte Carlo to scan the space of priors. On the light of these high redshift supernova data sets, we reconstruct w(z). A comparison between a sample including the latest results at z>1 and a sample without those results show the improvement achieved by observations of very high z supernovae. We present the prospects to measure the variation of dark energy density along z by this method.
Cho, Eugene N; Zhitomirsky, David; Han, Grace G D; Liu, Yun; Grossman, Jeffrey C
2017-03-15
Solar thermal fuels (STFs) harvest and store solar energy in a closed cycle system through conformational change of molecules and can release the energy in the form of heat on demand. With the aim of developing tunable and optimized STFs for solid-state applications, we designed three azobenzene derivatives functionalized with bulky aromatic groups (phenyl, biphenyl, and tert-butyl phenyl groups). In contrast to pristine azobenzene, which crystallizes and makes nonuniform films, the bulky azobenzene derivatives formed uniform amorphous films that can be charged and discharged with light and heat for many cycles. Thermal stability of the films, a critical metric for thermally triggerable STFs, was greatly increased by the bulky functionalization (up to 180 °C), and we were able to achieve record high energy density of 135 J/g for solid-state STFs, over a 30% improvement compared to previous solid-state reports. Furthermore, the chargeability in the solid state was improved, up to 80% charged from 40% charged in previous solid-state reports. Our results point toward molecular engineering as an effective method to increase energy storage in STFs, improve chargeability, and improve the thermal stability of the thin film.
Black Hole Radiation and Volume Statistical Entropy
Rabinowitz, M
2005-01-01
The simplest possible equations for Hawking radiation, and other black hole radiated power is derived in terms of black hole density. Black hole density also leads to the simplest possible model of a gas of elementary constituents confined inside a gravitational bottle of Schwarzchild radius at tremendous pressure, which yields identically the same functional dependence as the traditional black hole entropy. Variations of Sbh are can be obtained which depend on the occupancy of phase space cells. A relation is derived between the constituent momenta and the black hole radius RH