Search results for "Point particle"
showing 10 items of 15 documents
The electromagnetic field of an accelerated charge in the proper reference frame of a noninertial observer
1989
The Lienard-Wiechert formulae for the electric and magnetic fields of an accelerated charge moving along an arbitrary world-line are generalized so that they can be applied by noninertial observers using accelerating and rotating reference frames. For this purpose, a relativistic coordinate-independent formalism suggested by DeFacio, Dennis and Eetzloff is extended to the description of all kinematical aspects required in the theory of the retarded fields of a point charge. The generalized Lienard-Wiechert formula is applied to a number of special situations, demonstrating that it allows a lucid and concise treatment of a number of subtle problems such as the role of the «relativity of acce…
Towards the Quantitative Prediction of the Phase Behavior of Polymer Solutions by Computer Simulation
2009
The phase diagram of polymer solutions (cf. e.g. alkanes dissolved in supercritical carbon dioxide) is complicated, since there are four control parameters (temperature, pressure, monomer volume fraction, chain length of the polymer) and due to the interplay of liquid-vapor transitions and fluid-fluid unmixing. As a result I very intricate phase diagram topologies can result. An attempt to develop coarse-1 grained models that can deal with this task will be described. As usual, the polymers I will be modelled as off-lattice bead-spring chains, where several chemical monomers I are integrated into one effective bond, torsional degrees of freedom being dis-I regarded. But also a coarse-graine…
Calculation of the electrostatic field in a dielectric-loaded waveguide due to an arbitrary charge distribution on the dielectric layer
2016
The goal of this paper is to study the electrostatic field due to an arbitrary charge distribution on a dielectric layer in a dielectric-loaded rectangular waveguide. In order to obtain this electrostatic field, the potential due to a point charge on the dielectric layer is solved in advance. The high computational complexity of this problem requires the use of different numerical integration techniques (e.g., Filon, Gauss-Kronrod, Lobatto, …) and interpolation methods. Using the principle of superposition, the potential due to an arbitrary charge distribution on a dielectric layer is obtained by adding the individual contribution of each point charge. Finally, a numerical differentiation o…
Classical electromagnetic radiation in noninertial reference frames
1991
Customarily electromagnetic radiation is defined with reference to some inertial laboratory frame. But such a definition is too narrow to be applicable to questions concerning accelerated observers,e.g. why an accelerated observer does not receive radiation from a co-accelerating charge. It is shown in this paper that a radiation concept introduced for inertial observers by Rohrlich and Teitelboim allows an extension to noninertial (accelerating and rotating) reference frames in a natural way. The generalized concept is explicitly dependent on the proper acceleration and the rotation of the observer’s laboratory frame. The case of radiation due to an accelerated point charge is treated in f…
SIMPRE: A software package to calculate crystal field parameters, energy levels, and magnetic properties on mononuclear lanthanoid complexes based on…
2013
This work presents a fortran77 code based on an effective electrostatic model of point charges around a rare earth ion. The program calculates the full set of crystal field parameters, energy levels spectrum, and wave functions, as well as the magnetic properties such as the magnetization, the temperature dependence of the magnetic susceptibility, and the Schottky contribution to the specific heat. It is designed for real systems that need not bear ideal symmetry and it is able to determine the easy axis of magnetization. Its systematic application to different coordination environments allows magneto-structural studies. The package has already been successfully applied to several mononucle…
Determination of the η-transition form factor in the γp→pη→pγe+e− reaction
2011
The Dalitz decay η→γe+e− has been measured using the combined Crystal Ball and TAPS photon detector setup at the electron accelerator MAMI-C. Compared to the most recent transition form-factor measurement in the e+e− channel, statistics have been improved by one order of magnitude. The e+e− invariant mass distribution shows a deviation from the QED prediction for a point-like particle, which can be described by a form-factor. Using the usual monopole transition form-factor parameterization, F(m2)=(1−m2/Λ2)−1, a value of Λ−2=(1.92±0.35(stat)±0.13(syst)) GeV−2 has been determined. This value is in good agreement with a recent measurement of the η Dalitz decay in the μ+μ− channel and with rece…
The Action Principle in Classical Electrodynamics
2001
The main purpose of this chapter is to consider the formulation of a relativistic point particle in classical electrodynamics from the viewpoint of Lagrangian mechanics. Here, the utility of Schwinger’s action principle is illustrated by employing three different kinds of action to derive the equations of motion and the associated surface terms.
Modell einer Coulombschen Ladung in der nichtlinearen Feldtheorie
1960
>The nonlinear field theory developed by K. Bechert has solutions which correspond to a charged particle whose charge is represented by a charge density which is zero in the particle center, increases to a maximum against the particle edges, and then again decreases. The linear expansion of the particles was measured by the characteristic length L, which accurately represents the classical particle radius; for an electron L is equal to the classical electron radius. The physical magnitudes integrated over a random spatial area are all infinite. In the theory a dimensionless number of the order-of-magnitude of 10/ sup 4//sup 2/ occurs. The particle was held together by gravitational forces w…
Spherical solid model for muon and hydrogen in metals
1979
The spherical solid model and the spin density functional formalism have been applied to calculate the screening of a positive point charge at different lattice sites in Al, Na and Cu. Results are obtained for the Knight shift, the electric field gradient, the heat of solution and the diffusion barrier. It is found essential to use the spin-polarised form to evaluate the Knight shift, especially at low metallic densities and for impurities with a high nuclear charge. Both the Knight shift and the electric field gradient are found to be markedly different for substitutional and interstitial positions. The calculated heat of solution of hydrogen is lowest for the octahedral position in FCC Al…
Investigations of Superheavy Quasiatoms via Spectroscopy of δ Rays and Positrons
1984
There exists a long-standing and very interesting problem in atomic physics, namely, the question: What is the binding energy of an electron if the strength of the Coulomb potential exceeds Zα = 1? According to the Dirac-Sommerfeld fine-structure formula for a point charge $$E = {m_e}{c^2}{[1 - {(Z\alpha )^2}]^{1/2}}$$ (1) the total energy of the lowest bound Is-state becomes imaginary for Zα > 1. But even as early as 1945 it was realized(59) that this property of Eq. (1) is caused by the singularity of the Coulomb potential at the origin. Assuming a realistic charge distribution of the nucleus there is no restriction suc as Zα < 1 for the binding energy. Recent calculations show (cf., e.g.…