Wave Packet
Mostrando 1-12 de 14 artigos, teses e dissertações.
-
1. Propagation of vibrational modes in classical harmonic lattice with correlated disorder
Abstract: The vibrational modes with nonzero frequency are localized in harmonic lattice with disordered masses. In our work, we investigated numerically the propagation of vibrational energy in harmonic lattice with long-range correlated disordered masses, which are randomly distributed with power law spectrum S ( k ) ∝ k − α. For α = 0, a standar
An. Acad. Bras. Ciênc.. Publicado em: 01/07/2019
-
2. Estudo teórico da estrutura eletrônica e da dinâmica induzida por lasers da molécula de HCl
Potential energy and dipole moment curves for the HCl molecule were computed. Calculations were performed at different levels of theory (DFT, MRCI). Spectroscopic properties are reported and compared with experimental data, for validating the theoretical approaches. Interaction of infrared radiation with HCl is simulated using the wave packet formalism. The
Quím. Nova. Publicado em: 2013
-
3. Gas de Bose diluido fracamente confinado / Dilute Bose gas weakly confined
A critical study of atomic Bose-Einstein condensates (BECs) is presented. Taking as a starting point the physics of the free gas, we study the effect of weakly confining potentials. Two cases were studied in detail: i) an atomic gas in a finite square well potential with a few bound states; and ii) a system confined in two-dimensions by an isotropic harmonic
Publicado em: 2010
-
4. Interatomic coulombic decay: a short review
The transition process of the interatomic Coulombic decay (ICD), is an electronic radiationless transition process, driving molecular complexes or clusters to a doubly ionized final state. This process differs from the Auger effect, because it takes place from a neutral monomer after the absorption of a released amount energy of the neighboring monomer in th
Brazilian Journal of Physics. Publicado em: 2009-09
-
5. Quantum percolation of one-electron states in power-law diluted chains
We investigate the nature of one-electron eigenstates in power-law diluted chains for which the probability of occurrence of a bond between sites separated by a distance r decays as p(r) = 1/r1+sigma. Using an exact diagonalization scheme on finite chains, we compute the spreading of an initially localized wave-packet, the time dependent participation number
Brazilian Journal of Physics. Publicado em: 2008-03
-
6. Wave packet description of neutrino oscillation in a progenitor star supernova environment
In this work we briefly review the wave packet approach of two generation neutrino oscillation, aiming its description in a progenitor star supernova environment. We begin calculating the wave packet size in many situations: solar and supernova plasma medium, considering nuclear interactions, as well as accelerators and reactors. This quantity is important t
Brazilian Journal of Physics. Publicado em: 2007-12
-
7. Dois Elétrons em cadeias cristalinas e aperiódicas: efeito de campo elétricos.
Recently much attention was drived to the interplay between dynamical localization and electron-electron interaction. In this master degree thesis we contribute to futher understanding of the phenomenon of electronic Bloch oscillations in both periodic and apperiodic low-dimensional systems with two interacting electrons. We followed two distinct quantum for
Publicado em: 2007
-
8. Oscilação de neutrinos no formalismo de pacotes de onda / Neutrino oscillation in the wave packet approach
Generally, we study neutrino oscillation phenomenon using the plane wave formalism, which successfully treats the solar neutrino case, the reactor and accelerator cases. However, a more complete description of neutrino oscillation must consider a wave packet approach. This work analyses both formalisms: the plane wave and the wave packet in vacuum and matter
Publicado em: 2006
-
9. Quantum chaos, dynamical stability and decoherence
We discuss the stability of quantum motion under system's perturbations in the light of the corresponding classical behavior. In particular we focus our attention on the so called "fidelity" or Loschmidt echo, its relation with the decay of correlations, and discuss the quantum-classical correspondence. We then report on the numerical simulation of the doubl
Brazilian Journal of Physics. Publicado em: 2005-06
-
10. Semiclassical propagation of coherent states / Propagação semiclassica de estados coerentes
This thesis addresses di®erent aspects of the semiclassical propagation of coherent states. We have derived a general expression for the propagator connecting these states which, di®erently from previous formulae in the literature, is valid for packets of arbitrary widths. The result, obtained via functional integration, depends on classical trajectories i
Publicado em: 2005
-
11. Stochastic diffusion of energetic ions due to incoherent lower hybrid waves
In the present paper we discuss stochastic diffusion of energetic ions by a set of lower hybrid waves with frequencies close to each other and random phases which change along the time evolution of the system. We obtain efficient long term diffusion in velocity space, which is more representative of the diffusion produced by a continuous wave packet than the
Brazilian Journal of Physics. Publicado em: 2003-12
-
12. Emaranhamento e caos em um sistema de dois spins
In this project we have studied a two spin system under an anisotropic Heisenberg interaction and external magnetic fields acting on each spin separately. We have been able to relate fast decoherence of a quantum subsystem with the presence of chaos in the corresponding classical system. Such an association has been done making use of the coherent state repr
Publicado em: 2002