Tight Binding Hamiltonian
Mostrando 1-11 de 11 artigos, teses e dissertações.
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1. Transporte eletrônico e propriedades termodinâmicas de nanobiomoléculas
Nesta tese, investigamos a transmissividade e as características de corrente como função da diferença de potencial, no contexto da ligação forte, em seqüências de dupla fita do DNA. Com o intuito de investigar a relevância das correlações subjacentes nas distribuições dos nucleotídeos, comparamos os resultados de uma seqüência genômica do DN
Publicado em: 2009
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2. Propriedades termo-eletrônicas da molécula do DNA
This thesis presents a comprehensive and up-to-date account of some physical properties of the DNA molecule, such as its thermodynamics (specific heat) and electronic (electronic transmissivity and localization factor, among others) aspects. The DNA molecule can be considered as a symbolic sequence of a four letter alphabet, namely guanine (G), adenine (A),
Publicado em: 2008
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3. Magnetic field effects of double-walled carbon nanotubes
A theoretical discussion of electronic and transport properties of a particular family of double-wall carbon nanotubes, named commensurate structures of the armchair type (n,n)@(2n,2n) is addressed. A single pi-band tight binding hamiltonian is considered and the magnetic field is theoretically described by following the Peierls approximation into the hoppin
Brazilian Journal of Physics. Publicado em: 2006-09
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4. A selfconsistent calculation of the transport properties of a double barrier spin filter
A double barrier resonant tunneling device in which the well is made of a semi-magnetic material can work as an efficient spin filter. Today it is possible to make semiconductors that are ferromagnetic at room temperature. Therefore the device studied here has a great potential to be used as a polarizer, an analyzer and other spintronic applications. We disc
Brazilian Journal of Physics. Publicado em: 2006-06
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5. Hydrogenated Ge nanocrystals: band gap evolution with increasing size
The electronic band structure of various Ge quantum wires of different sizes, with hydrogenated surfaces, is studied using a nearest-neighbor empirical tight-binding Hamiltonian by means of a sp³s* atomic orbitals basis set. We suppose that the nanostructures have the same lattice structure and the same interatomic distance as in bulk Ge and that all the da
Brazilian Journal of Physics. Publicado em: 2006-06
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6. EVOLUTIONARY SYNTHESIS IN NANOTECHNOLOGY / SÍNTESE EVOLUCIONÁRIA EM NANOTECNOLOGIA
The first Nanotechnology concepts were introduced by the American physicist Richard Feynman in 1959, in his famous lecture entitled There´s plenty of room at the bottom. Computational Intelligence has been successfully used in various areas in the academic and industrial worlds. This work investigates the potential of Genetic Algorithms in the optimization
Publicado em: 2006
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7. Carbon nanotube structures: Y-junctions and nanorings
The possibility of coupling two Y-junctions of carbon nanotubes, forming a type of nanotube ring is addressed here. Recent experimental evidences of growing carbon nanotube structures forming basically Y-kind junctions give support to this theoretical proposition. A single-band tight-binding Hamiltonian is considered and local electronic properties are inves
Brazilian Journal of Physics. Publicado em: 2004-06
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8. Electric and magnetic field effects on electronic structure of straight and toroidal carbon nanotubes
Nanotubes have been proved as promising candidates for many technological applications in the nanoscale word and different physical properties have been studied and measured along the few recent years. Here we investigate the role played by external magnetic and electric fields on the electronic properties of toroidal and cylindrical straight carbon nanotube
Brazilian Journal of Physics. Publicado em: 2004-06
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9. ELECTRONIC CORRELATION IN QUANTUM DOTS SYSTEMS / CORRELAÇÃO ELETRÔNICA EM SISTEMAS DE PONTOS QUÂNTICOS
In this thesis we investigate the effects of the eletron- eletron interaction on the transport properties of nanosystems. In particular, we study systems constituted by two quantum dots conected to leads, in different topologies. Our main interest is to study the effects of the Kondo regime and the electronic phase on the conductance. In the configuration wh
Publicado em: 2004
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10. Heteroestruturas de semicondutores na presença de campos AC intensos
The study of coupling of the electronic structure of a semiconductor heterostructure with strong AC fields, is the main purpose of the present work. The interaction of the electronic structure of a heterostructure with an AC field of determined frequency is given by a time-independent Hamiltonian which replaces a semiclassic time- dependent Hamiltonian. The
Publicado em: 1998
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11. Estados eletronicos de superficie e interfaces em semicondutores : Si-Sno2
We develop a technique to calculate the density of state of surfaces and interfaces. The method used here is the tight-binding Hamiltonian based on the Slater-Koster approach. The Green functions, which arise from the formalism of the scattering theory, are decoupled through the renormalization s procedure. We study the ideal surface (100) of Si and SnO2, an
Publicado em: 1984