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Doctoral Thesis
DOI
https://doi.org/10.11606/T.54.1980.tde-19082014-105000
Document
Author
Full name
Joao Medeiros e Silva
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 1980
Supervisor
Committee
Mokross, Bernhard Joachim (President)
Aegerter, Michel Andre
Brandi, Humberto Siqueira
Ferreira, Guilherme Fontes Leal
Ferreira, Ricardo de Carvalho
Title in Portuguese
Cristal de Wigner Blindado
Keywords in Portuguese
Cristal de Wigner
Dinâmica de rede
Abstract in Portuguese
No presente trabalho propomos e estudamos um modelo teórico que denominamos Cristal de Wigner Blindado. Assumindo para este sistema uma estrutura ordenada, nos foi possível verificar a ocorrência de uma transição de fase entre as estruturas bcc e fcc, para este modelo em função da densidade e/ou do parâmetro de blindagem. Após esta análise estática nos estendemos aos aspectos dinâmicos. Determinamos os modos normais para estas estruturas obtendo espectros de frequência para diversas blindagem e/ou densidade. Levando o parâmetro de blindagem para o limite zero, recuperamos diversos resultados conhecidos para o Cristal de Wigner. Isto era esperado urna vez que este modelo apenas difere do nosso pela natureza das interações, que neste caso são puramente coulombianas, sem blindagem. Além disto, nos foi possível efetuar comparação com sistemas reais formados por esferas de poliestireno em suspensão aquosa, permitindo-nos concluir que o modelo por nós proposto é aplicável aos mesmos
Title in English
Screened Wigner Lattice
Keywords in English
Lattice Dynamics
Wigner Lattice
Abstract in English
We present and develop a theoretical model which we designate Screened Wigner Lattice (SWL). In the ordered phase of this system we were able to predict a bcc-fcc transition, by varying the screening parameter and/or the density. After this static analysis we calculated the normal modes of such crystals and got the frequency spectra in function of the screening and/or density. Taking for the screening parameter the limit zero we reproduced several results already known for the Wigner Lattice (WL). This was expected since the only difference between the SWL and WL models consists on the nature of the interaction, some of our theoretical results with experimental data obtained for crystals formed by polystyrene spheres in aqueous suspension. The agreement allows us to conclude that the SWL model applies for such systems
 
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Publishing Date
2014-08-21
 
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