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Autor Maciá Barber, Enrique Alfonso |
Documentos disponibles escritos por este autor (55)
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Landauro, C.V. ; Maciá Barber, Enrique Alfonso ; Solbrig, H. | American Physical Society | 2003-05-01We investigate by analytical means the electronic transport properties of approximants and quasicrystals. The spectral resistivity is modeled by Lorentz functions in agreement with realistic ab initio calculations (linear muffin-tin orbital basi[...]texto impreso
We numerically investigate the effects of inhomogeneities in the energy spectrum of aperiodic semiconductor superlattices, focusing our attention on Thue-Morse and Fibonacci sequences. In the absence of disorder, the corresponding electronic spe[...]texto impreso
Aperiodic order plays a very significant role in biology, as it determines most informative content of genomes. Amongst the various physical, chemical or biological phenomena that might be inferred from sequence correlations, charge transfer pro[...]texto impreso
Quasicrystals are a class of ordered solids made of typical metallic atoms but they do not exhibit the physical properties that usually signal the presence of metallic bonding, and their electrical and thermal transport properties resemble a mor[...]texto impreso
In this work, we show that the fundamental structure of the electronic energy spectrum of binary Fibonacci quasicrystals can be decomposed in terms of two main contributions, stemming from two related characteristic symmetries. The algebraic app[...]texto impreso
The thermoelectric power of trimer oligonucleotides connected in between metallic contacts at different temperatures is theoretically studied. The obtained analytical expressions reveal the existence of important resonance effects leading to a s[...]texto impreso
In this work we present a prospective study on the possible use of certain quasicrystalline alloys in order to improve the efficiency of segmented thermoelectric generators. To this end, we obtain a closed analytical expression for their compati[...]texto impreso
Maciá Barber, Enrique Alfonso ; Triozon, François ; Roche, Stephan | American Physical Society | 2005-03We report on theoretical results about contact-dependent effects and tunneling currents through DNA molecules. A tetranucleotide PolyGACT chain, connected in between metallic contacts, is studied as a generic case, and compared to other periodic[...]texto impreso
Domínguez-Adame Acosta, Francisco ; Maciá Barber, Enrique Alfonso ; Sánchez, Angel | American Physical Society | 1993-09-01Normal modes of one-dimensional disordered chains with two couplings, one of them assigned at random to pairs in an otherwise perfect chain, are investigated. We diagonalize the dynamical matrix to find the normal modes and to study their spatia[...]texto impreso
The thermoelectric performance of PolyG-PolyC and PolyA-PolyT double-stranded chains connected between organic contacts at different temperatures is theoretically studied on the basis of an effective model Hamiltonian. The obtained analytical ex[...]texto impreso
In this work we present a theoretical study on the thermal and electrical conductivities of quasicrystals. By considering a realistic model for the spectral conductivity we derive closed analytical expressions for the transport coefficients whic[...]texto impreso
Díez, E. ; Domínguez-Adame Acosta, Francisco ; Maciá Barber, Enrique Alfonso ; Sánchez, A. | American Physical Society | 1996-12-15We present a detailed study of the dynamics of electronic wave packets in Fibonacci semiconductor superlattices, both in flat band conditions and subject to homogeneous electric fields perpendicular to the layers. Coherent propagation of electro[...]texto impreso
Maciá Barber, Enrique Alfonso ; Domínguez-Adame Acosta, Francisco ; Sánchez, Angel | American Physical Society | 1994-04-01We derive a discrete Hamiltonian describing a Fibonacci superlattice in which the electronic potential is taken to be an array of equally spaced delta potentials, whose strengths modulate the chemical composition in the growth direction. In this[...]texto impreso
In this work we consider the combined effect of helical structure and base-pair twist motion on charge transfer through duplex DNA at low temperatures. We present a fully analytical treatment of charge-lattice coupled dynamics in terms of neares[...]texto impreso
We consider a class of synthetic DNA molecules based on a quasiperiodic arrangement of their constituent nucleotides. Making use of a two-step renormalization scheme the double-stranded DNA molecule is modeled in terms of a one-dimensional effec[...]texto impreso
Domínguez-Adame Acosta, Francisco ; Maciá Barber, Enrique Alfonso ; Méndez Martín, Bianchi | Elsevier Science BV | 1994-10-31We study the electronic structure of a new type of Fibonacci superlattice based on Si delta-doped GaAs. Assuming that delta-doped layers are equally spaced, quasiperiodicity is introduced by selecting two different donor concentrations and arran[...]texto impreso
Domínguez-Adame Acosta, Francisco ; Méndez Martín, Bianchi ; Maciá Barber, Enrique Alfonso | IOP publishing ltd | 1994-03The electron dynamics and the density of states of both single and periodic Si delta-doped GaAs subject to an applied electric field are studied theoretically. The space charge potential due to delta-doping is obtained by means of the semiclassi[...]texto impreso
A detailed study of charge transport properties of synthetic and genomic DNA sequences is reported. Genomic sequences of the Chromosome 22, lambda-bacteriophage, and D1s80 genes of Human and Pygmy chimpanzee are considered in this work, and comp[...]texto impreso
In this work we extend the algebraic approach introduced in the context of general Fibonacci systems [E. Maciá and F. Domínguez-Adame, Phys. Rev. Lett. 76, 2957 (1996)] to analytically study the transmission coefficient of a subset of states in [...]texto impreso
Maciá Barber, Enrique Alfonso ; Domínguez-Adame Acosta, Francisco ; Sánchez, Angel | American Physical Soc | 1994-08We study the relationship between the electronic spectrum structure and the configurational order of one-dimensional quasiperiodic systems. We take the Fibonacci case as a specific example, but the ideas outlined here may be useful to accurately[...]texto impreso
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Sánchez, Angel ; Maciá Barber, Enrique Alfonso ; Domínguez-Adame Acosta, Francisco | American Physical Society | 1994-06-01We consider the electron dynamics and transport properties of one-dimensional continuous models with random, short-range correlated impurities. We develop a generalized Poincare map formalism to cast the Schrodinger equation for any potential in[...]texto impreso
Sánchez, A. ; Domínguez-Adame Acosta, Francisco ; Maciá Barber, Enrique Alfonso | American Physical Society | 1995-01-01Incoherent transport of excitations in one-dimensional disordered lattices with pairs of traps placed at random is studied by numerically solving the corresponding aster equation. Results are compared to the case of lattices with the same concen[...]texto impreso
Maciá Barber, Enrique Alfonso ; Domínguez-Adame Acosta, Francisco | American Physical Society | 1994-12-15Exciton optical absorption in self-similar aperiodic one-dimensional systems is considered, focusing our attention on Thue-Morse and Fibonacci lattices as canonical examples. The absorption line shape is evaluated by solving the microscopic equa[...]texto impreso
Domínguez-Adame Acosta, Francisco ; Méndez Martín, Bianchi ; Sánchez, A. ; Maciá Barber, Enrique Alfonso | American Physical Society | 1994-02-01Numerical investigations of the trapping of Frenkel excitons in one-dimensional lattices with interstitial traps randomly placed in pairs are presented. The probabilities of finding the exciton both in the q = 0 mode P(t) and in any mode Q(t) ha[...]texto impreso
In this work we present a prospective study on the potential capabilities of optical devices based on Fibonacci dielectric multilayers. We perform a detailed analytical comparison of the linear optical response of periodic versus quasiperiodic m[...]texto impreso
Domínguez-Adame Acosta, Francisco ; Maciá Barber, Enrique Alfonso ; Méndez Martín, Bianchi ; Roy, C.L. ; Khan, A. | IOP publishing ltd | 1995-06We report the theoretical electronic structure of Fibonacci superlattices of narrow-gap III-V semiconductors. The electron dynamics is accurately described within the envelope-function approximation in a two-band model. Quasiperiodicity is intro[...]texto impreso
Domínguez-Adame Acosta, Francisco ; Maciá Barber, Enrique Alfonso | American Physical Society | 1996-05-15We study motion and capture of excitons in self-similar linear systems in which interstitial traps are arranged according to an aperiodic sequence, focusing our attention on Fibonacci and Thue-Morse systems as canonical examples. The decay of th[...]texto impreso
We study the phonon dynamics of Fibonacci heterostructures where two kinds of order (namely, periodic and quasiperiodic) coexist in the same sample at different length scales. We derive analytical expressions describing the dispersion relation o[...]texto impreso
Domínguez-Adame Acosta, Francisco ; Maciá Barber, Enrique Alfonso ; Sánchez, Angel | American Physical Society | 1995-01-01Incoherent exciton dynamics in one-dimensional perfect lattices with traps at sites arranged according to aperiodic deterministic sequences is studied. We focus our attention on Thue-Morse and Fibonacci systems as canonical examples of self-simi[...]texto impreso
Roche, S. ; Bicout, D. ; Maciá Barber, Enrique Alfonso ; Kats, E. | American Physical Society | 2003-10-28We address the relation between long-range correlations and charge transfer efficiency in aperiodic artificial or genomic DNA sequences. Coherent charge transfer through the highest occupied molecular orbital states of the guanine nucleotide is [...]texto impreso
We present a theoretical analysis of quasicrystals (QCs) as potential thermoelectric materials. We consider a self-similar density of states model and extend the framework introduced in [G. D. Mahan and J. O. Sofo, Proc. Natl. Acad. Sci. U.S.A. [...]texto impreso
A model for the electronic structure of icosahedral quasicrystals is proposed on the basis of a number of pertinent experimental results. From this model we obtain a closed analytical expression for the electrical conductivity accurately describ[...]texto impreso
Maciá Barber, Enrique Alfonso ; Takeuchi, Tsunehiro ; Otagiri, Toshio | American Physical Society | 2005-11The electronic structure of a quasicrystalline approximant sample is analyzed by means of a combined study of different experimental transport curves within a phenomenological approach. The main features of the obtained spectral conductivity are[...]texto impreso
Domínguez-Adame Acosta, Francisco ; Méndez Martín, Bianchi ; Maciá Barber, Enrique Alfonso ; González, M. A. | Taylor & Francis Ltd | 1991-12-10It is shown that nonlocal separable potentials may be used to study bound states of particles in multicentre potentials. The binding energy is obtained in a closed form. The cases of H_2+ ion and polymer chains are discussed in detail and result[...]texto impreso
Domínguez-Adame Acosta, Francisco ; Maciá Barber, Enrique Alfonso ; Sánchez, Angel | American Physical Society | 1994-09-01Optical absorption in a random one-dimensional lattice in the presence of paired correlated disorder is studied. The absorption line shape is evaluated by solving the microscopic equations of motion of the Frenkel-exciton problem in the lattice.[...]texto impreso
In this work we analyze the potential role of quasicrystals and related alloys in thermoelectric material research. Relatively large figure of merit values are expected for those samples exhibiting two properly located narrow features in the den[...]texto impreso
The presence of synchronized, collective twist motions of the Watson-Crick base pairs in DNA duplexes (helicoidal standing waves) can efficiently enhance the pi-pi orbital overlapping between nonconsecutive base pairs via a long-range, phonon-co[...]texto impreso
We report on the possibility of modulating the transport properties of critical normal modes in Fibonacci quasicrystals by using the mass ratio as a tuning parameter. The relationship between the spatial structure and the transport properties of[...]texto impreso
Maciá Barber, Enrique Alfonso ; Domínguez-Adame Acosta, Francisco | American Physical Society | 1996-04-15We report on a new class of critical states in the energy spectrum of general Fibonacci systems. By introducing a transfer matrix renormalization technique, we prove that the charge distribution of these states spreads over the whole system, sho[...]texto impreso
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In this work we introduce a similarity transformation acting on transfer matrices describing the propagation of elementary excitations through either periodic or Fibonacci lattices. The proposed transformation can act at two different scale leng[...]texto impreso
A spectral classification of general one-dimensional binary aperiodic crystals (BACs) based on both their diffraction patterns and energy spectrum measures is introduced along with a systematic comparison of the zeroth-order energy spectrum main[...]texto impreso
Sáchez, A. ; Maciá Barber, Enrique Alfonso ; Domínguez-Adame Acosta, Francisco | American Physical Society | 1994-01-01We consider the electron dynamics and transport properties of one-dimensional continuous models with random, short-range correlated impurities. We develop a generalized Poincare map formalism to cast the Schrodinger equation for any potential in[...]texto impreso
The validity of the Wiedemann-Franz law (WFL) for icosahedral quasicrystals belonging to the families AlCu(Fe,Ru) and AlPd(Mn,Re) is discussed. We exploit some characteristic features in the electronic structure in order to obtain closed analyti[...]texto impreso
In this work we present a theoretical study on the possible use of quasicrystals as potential thermoelectric materials. By considering a suitable model for the spectral conductivity we show that high values of the thermoelectric figure of merit,[...]texto impreso
In this work we consider the range of validity of the Wiedemann-Franz law (WFL) in quasicrystals, approximant phases, and giant unit-cell complex metallic alloys. In the limit of very low temperatures the WFL is satisfied, as expected, but as th[...]texto impreso
We consider a general Fibonacci quasicrystal (FQC) in which both the masses and the elastic constants are aperiodically arranged. Making use of a suitable decimation scheme, inspired by real-space renormalization-group concepts, we obtain closed[...]texto impreso
Aperiodic photonic crystals can open up novel routes for more efficient photon management due to increased degrees of freedom in their design along with the unique properties brought about by the long-range aperiodic order as compared to their p[...]texto impreso
In this work we present a theoretical study on the composition dependence of the thermoelectric figure of merit (ZT) of icosahedral AlPdRe quasicrystals. From our study we conclude that band-structure effects play a significant role in determini[...]texto impreso
In this work, we introduce a phenomenological model describing the thermoelectric power of icosahedral quasicrystals. On the basis of a realistic model for the spectral conductivity, obtained from ab initio band-structure calculations [C. Landau[...]texto impreso
We report on a theoretical study of the electronic structure of quasiperiodic, quasi-one-dimensional systems where fully three-dimensional interaction potentials are taken into account. In our approach, the actual physical potential acting upon [...]texto impreso
Méndez Martín, Bianchi ; Domínguez-Adame Acosta, Francisco ; Maciá Barber, Enrique Alfonso | IOP publishing ltd | 1993-01-07We show that the discretized forms of the Schrodinger and the Dirac equations for an arbitrary potential in one dimension are equivalent to the Poincare map of the corresponding wave equation for an array of delta-function potentials. Therefore,[...]texto impreso
In this work we report the existence of certain universal features in the temperature dependence of the electrical conductivity of Al-transition-metal icosahedral quasicrystals, extending the results previously reported on the inverse Matthiesse[...]texto impreso
We have numerically computed the reflectivity of X-rays incident normally onto Fibonacci multilayers, and compared the results with those obtained in periodic approximant multilayers. The constituent layers are of low and high refractive indices[...]