1,775 research outputs found
Clocking Koufax
In lieu of an abstract, below is the essay\u27s first paragraph.
Walking out of the tunnels of Baltimore’s Memorial Stadium, even after the roaring crowds had departed in compressed streams of red taillights, was the best part of the evening, John Angelina had decided early in the baseball season. Especially now that the Orioles were headed for a pennant and possibly the World Series, the line of groupies would wait for the pitchers. Not that the other players or positions were any less attractive, it was just something about the pitchers. Particularly that battery of pitchers that year that would in fact find heroes in all unlikely places and circumstances; that year that would deliver a resounding win at the World Series against the legendary Los Angeles Dodgers and the brilliant Sandy Koufax
Alamogordo
In lieu of an abstract, below is the essay\u27s first paragraph.
The road into Clovis had been tortuous but tinted with the colors of the New Mexico desert subtly touched by the incipient autumn. Driving a military Jeep with a comrade from their former B-17 squadrons in Europe, Joseph Angelina thought how different it would be to fly in this clear, dry air, so remarkably pure after his recent years of trying to locate enemy targets in cloudy and moody Europe
Multiplicity results for some nonlinear Schroedinger equations with potentials
We prove some multiplicity results for a nonlinear equation of Schroedinger
type with potential function
Quantum Monte Carlo study of circular quantum dots in presence of Rashba interaction
We present the numerical Quantum Monte Carlo results for the ground state
energy of circular quantum dots in which Rashba spin-orbit iteraction is
present. Diffusion Monte Carlo with spin propagation is applied in order to
treat the spin-orbit interaction correctly, following previous work done in the
fieldof the two-dimensional electron gas. Together with ground state energies,
also numerical results for density and spin-density profiles are given
Interatomic Methods for the Dispersion Energy Derived from the Adiabatic Connection Fluctuation-Dissipation Theorem
Interatomic pairwise methods are currently among the most popular and
accurate ways to include dispersion energy in density functional theory (DFT)
calculations. However, when applied to more than two atoms, these methods are
still frequently perceived to be based on \textit{ad hoc} assumptions, rather
than a rigorous derivation from quantum mechanics. Starting from the adiabatic
connection fluctuation-dissipation (ACFD) theorem, an exact expression for the
electronic exchange-correlation energy, we demonstrate that the pairwise
interatomic dispersion energy for an arbitrary collection of isotropic
polarizable dipoles emerges from the second-order expansion of the ACFD
formula. Moreover, for a system of quantum harmonic oscillators coupled through
a dipole--dipole potential, we prove the equivalence between the full
interaction energy obtained from the Hamiltonian diagonalization and the ACFD
correlation energy in the random-phase approximation. This property makes the
Hamiltonian diagonalization an efficient method for the calculation of the
many-body dispersion energy. In addition, we show that the switching function
used to damp the dispersion interaction at short distances arises from a
short-range screened Coulomb potential, whose role is to account for the
spatial spread of the individual atomic dipole moments. By using the ACFD
formula we gain a deeper understanding of the approximations made in the
interatomic pairwise approaches, providing a powerful formalism for further
development of accurate and efficient methods for the calculation of the
dispersion energy
Gauge approach to the specific heat in the normal state of cuprates
Many experimental features of the electronic specific heat and entropy of
high Tc cuprates in the normal state, including the nontrivial temperature
dependence of the specific heat coefficient and negative intercept of the
extrapolated entropy to T=0 for underdoped cuprates, are reproduced using the
spin-charge gauge approach to the t-J model. The entropy turns out to be
basically due to fermionic excitations, but with a temperature dependence of
the specific heat coefficient controlled by fluctuations of a gauge field
coupling them to gapful bosonic excitations. In particular the negative
intercept of the extrapolated entropy at T=0 in the pseudogap ``phase'' is
attributed to the scalar component of the gauge field, which implements the
local no-double occupancy constraint.Comment: 5 pages, 5 figure
Long-range correlation energy calculated from coupled atomic response functions
An accurate determination of the electron correlation energy is essential for
describing the structure, stability, and function in a wide variety of systems,
ranging from gas-phase molecular assemblies to condensed matter and
organic/inorganic interfaces. Even small errors in the correlation energy can
have a large impact on the description of chemical and physical properties in
the systems of interest. In this context, the development of efficient
approaches for the accurate calculation of the long-range correlation energy
(and hence dispersion) is the main challenge. In the last years a number of
methods have been developed to augment density functional approximations via
dispersion energy corrections, but most of these approaches ignore the
intrinsic many-body nature of correlation effects, leading to inconsistent and
sometimes even qualitatively incorrect predictions. Here we build upon the
recent many-body dispersion (MBD) framework, which is intimately linked to the
random-phase approximation for the correlation energy. We separate the
correlation energy into short-range contributions that are modeled by
semi-local functionals and long-range contributions that are calculated by
mapping the complex all-electron problem onto a set of atomic response
functions coupled in the dipole approximation. We propose an effective
range-separation of the coupling between the atomic response functions that
extends the already broad applicability of the MBD method to non-metallic
materials with highly anisotropic responses, such as layered nanostructures.
Application to a variety of high-quality benchmark datasets illustrates the
accuracy and applicability of the improved MBD approach, which offers the
prospect of first-principles modeling of large structurally complex systems
with an accurate description of the long-range correlation energy.Comment: 15 pages, 3 figure
Spin-orbit excitations of quantum wells
Confinement asymmetry effects on the photoabsorption of a quantum well are
discussed by means of a sum-rules approach using a Hamiltonian including a
Rashba spin-orbt coupling. We show that while the strength of the excitation is
zero when the spin-orbit coupling is neglected, the inclusion of the spin-orbit
interaction gives rise to a non zero strength and mean excitation energy in the
far-infrared region. A simple expression for these quantities up to the second
order in the Rashba parameter was derived. The effect of two-body Coulomb
interaction is then studied by means of a Quantum Monte Carlo calculation,
showing that electron-electron correlations induce only a small deviation from
the independent particle model result
The Conformal Willmore Functional: a Perturbative Approach
The conformal Willmore functional (which is conformal invariant in general
Riemannian manifold ) is studied with a perturbative method: the
Lyapunov-Schmidt reduction. Existence of critical points is shown in ambient
manifolds -where is a metric close
and asymptotic to the euclidean one. With the same technique a non existence
result is proved in general Riemannian manifolds of dimension three.Comment: 34 pages; Journal of Geometric Analysis, on line first 23 September
201
Singularly perturbed elliptic problems with nonautonomous asymptotically linear nonlinearities
We consider a class of singularly perturbed elliptic problems with
nonautonomous asymptotically linear nonlinearities. The dependence on the
spatial coordinates comes from the presence of a potential and of a function
representing a saturation effect. We investigate the existence of nontrivial
nonnegative solutions concentrating around local minima of both the potential
and of the saturation function. Necessary conditions to locate the possible
concentration points are also given
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