Le problème de Coulomb-Dunkl dans le plan

Ce mémoire, composé d'un article en collaboration avec Monsieur Luc Vinet et Vincent X. Genest, est la suite du travail effectué sur les systèmes quantiques super-intégrables définis par des Hamiltoniens de type Dunkl. Plus particulièrement, ce mémoire vise l'analyse du problème de Coulomb-Dunkl dans le plan qui est une généralisation du système quantique de l'atome d'hydrogène impliquant des opérateurs de réflexion sur les variables x et y. Le modèle est défini par un potentiel en 1/r. Nous avons tout d'abord remarqué que l'Hamiltonien est séparable en coordonnées polaires et que les fonctions d'onde s'écrivent en termes de produits de polynômes de Laguerre généralisés et des harmoniques de Dunkl sur le cercle. L'algèbre générée par les opérateurs de symétrie nous a également permis de confirmer le caractère maximalement super-intégrable du problème de Coulomb-Dunkl. Nous avons aussi pu écrire explicitement les représentations de cette même algèbre. Nous avons finalement trouvé le spectre de l'énergie de manière algébrique.

Semiclassical theory of shot noise in ballistic n+in+ semiconductor structures: relevance of Pauli and long range Coulomb interactions

We work out a semiclassical theory of shot noise in ballistic n+-i-n+ semiconductor structures aiming at studying two fundamental physical correlations coming from Pauli exclusion principle and long-range Coulomb interaction. The theory provides a unifying scheme which, in addition to the current-voltage characteristics, describes the suppression of shot noise due to Pauli and Coulomb correlations in the whole range of system parameters and applied bias. The whole scenario is summarized by a phase diagram in the plane of two dimensionless variables related to the sample length and contact chemical potential. Here different regions of physical interest can be identified where only Coulomb or only Pauli correlations are active, or where both are present with different relevance. The predictions of the theory are proven to be fully corroborated by Monte Carlo simulations.

The role of energy correlations on Coulomb suppression in ballistic conductors contacted to degenerate reservoirs

Coulomb suppression of shot noise in a ballistic diode connected to degenerate ideal contacts is analyzed in terms of the correlations taking place between current fluctuations due to carriers injected with different energies. By using Monte Carlo simulations we show that at low frequencies the origin of Coulomb suppression can be traced back to the negative correlations existing between electrons injected with an energy close to that of the potential barrier present in the diode active region and all other carriers injected with higher energies. Correlations between electrons with energy above the potential barrier with the rest of electrons are found to influence significantly the spectra at high frequency in the cutoff region.

Effect of long-range Coulomb interaction on shot-noise suppression in ballistic transport

We present a microscopic analysis of shot-noise suppression due to long-range Coulomb interaction in semiconductor devices under ballistic transport conditions. An ensemble Monte Carlo simulator self-consistently coupled with a Poisson solver is used for the calculations. A wide range of injection-rate densities leading to different degrees of suppression is investigated. A sharp tendency of noise suppression at increasing injection densities is found to scale with a dimensionless Debye length related to the importance of space-charge effects in the structure.

An ab-initio calculation of the Coulomb explosion of N_2 after heavy-ion bombardement

Self-consistent-field calculations for the total potential energy of highly ionized N_2 molecules are presented. We compare these calculations to the experimentally observed energy released in the Coulomb explosion of ionized N_2 molecules created after collision with fast heavy ions. The most important electronic states of the fragment ions are determined.

Definición, hipótesis y experimentación en la Ley de Coulomb.

Fue el primero en descubrir las características de las fuerzas entre las cargas eléctricas. Su ley dice: la magnitud de cada una de las fuerzas eléctricas con que interactúan dos cargas puntuales en reposo es directamente proporcional al producto de la magnitud de ambas cargas ....

Demostración experimental de la Ley de Coulomb con el retroproyector.

Se realiza una demostración experimental de la Ley de Coulomb con el retroproyector. EI retroproyector de transparencias permite demostrar experimentalmente la Ley de Coulomb, de una manera rápida y precisa, a un conjunto numeroso de alumnos, de modo que todos ellos participen en la recogida de datos y en la interpretación de resultados. Se muestra esquemáticamente el montaje del experimento en una ilustración y se explica textualmente. La Ley de Coulomb solamente se puede aplicar a aquellas cargas cuyas dimensiones son despreciables comparadas con la distancia que las separa. En nuestros experimentos hemos comprobado que la Ley de Coulomb deja de cumplirse cuando la distancia de separación es inferior a cuatro veces el diámetro de las bolitas. Es decir, si el diámetro de éstas es de 1 cm, la distancia entre ambas bolitas debe ser mayor de 4 cm.

Comprobaci??n de la ley de Coulomb

Se presentan una serie de valores y se adjunta una gr??fica con el fin de representar la exactitud con la que se cumple la ley de Coulumb.

A Lei Orgánica de Educación : pasando revista a algúns dos seus pilares básicos. 'La ley Orgánica de Educación : pasando revista a algunos de sus pilares básicos'.

Resumen basado en el de la publicación

The mapping of the local contributions of Fermi and Coulomb correlation into intracule and extracule density distributions

The contributions of the correlated and uncorrelated components of the electron-pair density to atomic and molecular intracule I(r) and extracule E(R) densities and its Laplacian functions ∇2I(r) and ∇2E(R) are analyzed at the Hartree-Fock (HF) and configuration interaction (CI) levels of theory. The topologies of the uncorrelated components of these functions can be rationalized in terms of the corresponding one-electron densities. In contrast, by analyzing the correlated components of I(r) and E(R), namely, IC(r) and EC(R), the effect of electron Fermi and Coulomb correlation can be assessed at the HF and CI levels of theory. Moreover, the contribution of Coulomb correlation can be isolated by means of difference maps between IC(r) and EC(R) distributions calculated at the two levels of theory. As application examples, the He, Ne, and Ar atomic series, the C2-2, N2, O2+2 molecular series, and the C2H4 molecule have been investigated. For these atoms and molecules, it is found that Fermi correlation accounts for the main characteristics of IC(r) and EC(R), with Coulomb correlation increasing slightly the locality of these functions at the CI level of theory. Furthermore, IC(r), EC(R), and the associated Laplacian functions, reveal the short-ranged nature and high isotropy of Fermi and Coulomb correlation in atoms and molecules

Saudosismo dos anos setenta ou a arrogância da ignorância? O projecto de Decreto-lei de Educação Especial

Circulou em meios privados e ultimamente na Internet, de livre acesso, o projecto de Decreto-lei de Educação Especial, o qual merece algumas reflexões.