The effect of fixed discrete colloidal charges in the primitive model is investigated for spherical macroions. Instead of
considering a central bare charge, as it is traditionally done, we distribute discrete charges randomly on the sphere. We use molecular dynamics simulations to study this effect on various properties such as
overcharging, counterion distribution and diffusion. In the vicinity of the colloid surface the electrostatic potential may
considerably differ from the one obtained with a central charge. In the strong Coulomb coupling, we showed that the colloidal
charge discretization qualitatively influences the counterion distribution and leads to a strong colloidal charge-counterion
pair association. However, we found that charge inversion still persists even if strong pair association is observed.
Received 30 June 2000 and Received in final form 28 November 2000 相似文献
Summary A recent electrokinematics theorem leads to a general equation that, through an arbitrary irrotational fieldF, connects the motion of the electric-charge carriers, the internal potential and the dielectric properties of a physical
system with its external currents, voltages and powers. It has been proved for quasi-electrostatic fields,i.e. when the vector potential may be disregarded, and on the basis of classical mechanics. Here the theorem is extended to any
type of electromagnetic field and to quasi-relativistic quantum mechanics, in the case of many-particle systems for which,
moreover, the probability current density is suitably computed. The new equation so obtained, throughF, connects the external currents again with the internal electric permittivity and the scalar potential, in the same way as
in the preceding approach, and with the carrier velocity that, however, has to be computed according to quantum mechanics.
Moreover, it contains two new contributions, one deriving from the vector potential and the other from a current density arising
from the electron spin. By means of proper choices ofF, new expressions of the external currents of the system are determined as functions of the motion of its internal carriers.
In particular, the electrokinematics theorem is exploited to compute the output current in two-terminal nanoelectronic devices
in which, owing to the small sizes, quantum effects cannot be disregarded. Finally, such results, when they are applied to
the double-barrier tunnelling structures, allow us to show the splitting of the electron pulse into two uncorrelated pulses,
and as a consequence, to obtain a possible shot noise suppression, up to fifty per cent of the full shot noise. 相似文献
This paper summarizes and gives new extensions of previous work of the author and collaborative work of the author with Pierre Noyes. In the present paper we give a new generalization of the Feynman-Dyson derivation of electromagnetism in a non-commutative context. In this form, the theory extends to gauge fields and is entirely a consequence of a choice of the definition of derivatives as commutators and the choice of relationship between temporal and spatial derivatives. The paper uses diagrammatic techniques and discusses these issues in the context of discrete physical models. 相似文献
Nonlocal investigations are presented for exciton-photon coupling
in three-dimensional nano-spherical-particle photonic crystals in
compound lattices for a tailored dielectric environment to
optimize the optical properties of nano particles. The photonic
band structure can be modified by tuning the nano particle size
and the distance between two interlacing identical face-centered
sub-lattices making up the photonic crystal lattice. A complete
photonic band gap with a gap-midgap ratio as large as 40.82% has
been found in the wurzite structure under the current
investigation. 相似文献
The axioms of topological electromagnetism that were given by Hehl, Obukhov, and Rubilar are refined by the use of geometrical and topological notions that are found on orientable manifolds. The central problem of defining the spacetime electromagnetic constitutive law in terms of the geometrical and topological structure of the spacetime manifold is elaborated upon in the linear and nonlinear cases. The manner by which the spacetime metric might follow from the electromagnetic constitutive law is examined in the linear case. The possibility that the intersection form of the spacetime manifold might play a role in defining a topological basis for a nonlinear electromagnetic constitutive law is explored. The manner by which electromagnetic wave motion relates to the geometric structure is also discussed. 相似文献
This study investigates the theoretical aspects of the interaction between photons with mass and a mechanical oscillator as drawn within the framework of cavity optomechanics. The study employs Proca theory as the mathematical framework to initially describe the dynamics of massive photons in a Fabry-Perot cavity with a movable mass, both in classical and quantum scenarios. It quantifies the modifications induced by the nonzero photon mass, considering first- and second-order effects, and derives expressions for the amplification of radiation pressure resulting from the presence of nonzero photon mass. Additionally, it derives the Hamiltonian of the quantum optomechanical system, incorporating the effects of photon mass at first and second order. It anticipates that experimental realization of massive optomechanics can be achieved by utilizing Proca material, which is a spatio-temporally dispersive material that exhibits behavior equivalent to Proca theory in a vacuum, thus enabling the study of the interaction between massive photons and mechanical systems in cavity-based optomechanical setups (referred to as massive cavity optomechanics). The study presented here caters to a diverse audience with an interest in the analysis and measurement of interactions among massive objects at the quantum scale. 相似文献
In this paper, we discuss the formulation, stability and validation of a high-order non-dissipative discontinuous Galerkin (DG) method for solving Maxwell’s equations on non-conforming simplex meshes. The proposed method combines a centered approximation for the numerical fluxes at inter element boundaries, with either a second-order or a fourth-order leap-frog time integration scheme. Moreover, the interpolation degree is defined at the element level and the mesh is refined locally in a non-conforming way resulting in arbitrary-level hanging nodes. The method is proved to be stable and conserves a discrete counterpart of the electromagnetic energy for metallic cavities. Numerical experiments with high-order elements show the potential of the method. 相似文献