The ground state configurations and the ''normal'' mode spectra of a quasi-one-dimensional (Q1D) binary system of charged particles interacting through a screened Coulomb potential are presented. The minimum energy configurations were obtained analytically and independently through molecular dynamic simulations. A rich variety of ordered structures were found as a function of the screening parameter, the particle density, and the ratio between the charges of the distinct types of particles. Continuous and discontinuous structural transitions, as well as an unexpected symmetry breaking in the charge distribution are observed when the density of the system is changed. For near equal charges we found a disordered phase where a mixing of the two types of particles occurs. The phonon dispersion curves were calculated within the harmonic approximation for the one-and two-chain structures.

We consider a classical system of two-dimensional (2D) charged particles, interacting through a repulsive Yukawa potential exp(−r/λ)/r, and confined in a parabolic channel that limits the motion of the particles in the y direction. Along the x direction, the particles are subject to a periodic potential. The ground-state configurations and the normal-mode spectra of the system are obtained as a function of the periodicity and strength of the periodic potential (V 0 ) and density. An interesting set of tunable ground-state configurations are found, with firstor second-order structural transitions between them. A configuration with particles aligned, perpendicular to the x direction, in each minimum of the periodic potential is obtained for V 0 larger than some critical value that has a power-law dependence on the density. The phonon spectrum of different configurations was also calculated. A localization of the modes into a small frequency interval is observed for sufficiently large strength of the periodic potential, and a tunable gap in the phonon spectrum is found as a function of V 0 .

The diffusion of charged particles interacting through a repulsive Yukawa potential, exp(-r/λ)/r, confined by a parabolic potential in the y direction and subjected to a periodic substrate potential in the x direction is investigated. Langevin dynamic simulations are used to investigate the effect of the particle density, the amplitude of the periodic substrate, and the range of the interparticle interaction potential on the diffusive behavior of the particles. We found that in general the diffusion is suppressed with increasing the amplitude of the periodic potential, but for specific values of the strength of the substrate potential a remarkable increase of the diffusion is found with increasing the periodic potential amplitude. In addition, we found a strong dependence of the diffusion on the specific arrangement of the particles, e.g., single-chain versus multichain configuration. For certain particle configurations, a reentrant behavior of the diffusion is found as a function of the substrate strength due to structural transitions in the ordering of the particles.

Este trabalho conduz uma sugestão de ensino de ondas gravitacionais e interferência, para estudantes do ensino médio por meio da aplicação de uma sequência didática elaborada em consonância com a teoria da Aprendizagem significativa de David Ausubel e a teoria do Alinhamento construtivo de Biggs e Tang. Trata-se da análise da aplicação de uma sequência didática arquitetada para facilitar o trabalho docente desde o planejamento até a execução das ações e avaliação da aprendizagem de física, servindo assim como motivação para produções de novas sequências, construídas pelos próprios professores, tendo em consideração a apropriação desta ferramenta como arquétipo. É uma pesquisa de campo e reúne uma série de atividades, dentro e fora de sala de aula, sistematicamente preparadas e organizadas para o alcance dos objetivos de aprendizagem preliminarmente propostos, e utiliza-se de mecanismos como experimentação e utilização de TICs, dando ao estudante um papel mais ativo e autônomo na construção da própria aprendizagem tornando-a mais eficiente e significativa que é resultado pretendido.