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  • Inelastic scattering of light in superconducting Nb3Sn 
    Cuden, C. B. (Physical Review B, 1978)
    Theoretical and experimental results for the inelastic scattering of light off superconducting Nb3Sn are compared. It is found that the experimental results by Fraas et al. support well the theoretical work by Cuden, ...
  • Ge-Si and Ga-Al fractionation in Hawaiian volcanic rocks 
    Argollo, R. de; Schilling, J. G. (Geochimica et Cosmochimica ActaBrasil, 1978)
    Ge and Ga abundances in 19 petrologically and geochemically well-documented Hawaiian volcanic rocks were determined simultaneously by radiochemical neutron activation analysis. The data demonstrate a close affinity of Ga ...
  • Raman scattering of hght off a superconducting alloy containing paramagnetic impurities 
    Cuden, C. B.; Ramos, A. da. S. (Physical Review B, 1979)
    Raman scattering of light off a superconductor doped with a small concentration of paramagnetic impurities is discussed without recourse to the quasiparticle approximation. The scattering efficiency defined in terms of Kubo's ...
  • Electromagnetic absorption of light in superconducting Kondo alloys and superconductini alloys with strong electron —magnetic-impurity interaction 
    Cuden, C. B. (Physical Review B, 1980)
    E}ectro~agnetic absorption of light in superconducting Kondo alloys and in superconducting alloys with strong electron —magnetic-impurity interaction is discussed without recourse to the quasiparticle approximation. The ...
  • Use of 234U/238U disequilibrium in measuring chemical weathering rate of rocks 
    Moreira-Nordemann, Lycia Maria (Geochimica et Cosmochimica Acta, 1980)
    The rate of chemical weathering of rocks has been determined by using uranium as a natural isotopic tracer. The concentration of uranium and 234U/238U ratio in natural waters, rocks, and soils of the Preto river basin ...
  • Surface Raman scattering of the light in antiferromagnetic chromium 
    Cuden, C. B.; Mota, R. (Physical Review B, 1980)
    Raman scattering of light from the plane surface of antiferromagnetic chromium is discussed in terms of conventional second-order time-dependent perturbation theory. The scattering efficiency as a function of frequency and ...
  • New basis set for molecular calculations 11. A CNDO study of electric dipole moments and electronic valence population on AH and AB systems using the modified Slater orbitals. 
    Cabral, B. J. Costa; Vianna, J. D. M. (Journal of Physics B: Atomic and Molecular Physics, 1980)
    The modified Slater orbitals (MSO) basis set is utilised in calculation of the electronic valence population and the electric dipole moments in AH and AB systems, A and B being a second-row elements (from B to F). The ...
  • Low-temperature phase transition in Dy 
    Vasconcelos, J. (Physical Review B, 1982)
    We give a theoretical explanation for the low-temperature phase transition in Dy first experimentally observed by Rhyne et al. Our results are in excellent agreement with experimental observations. We also demonstrate that ...
  • Theoretical explanation of the Er C33-versus-temperature curve in the ordered phase near TN 
    Vasconcelos, J. (Physical Review B, 1982)
    We have developed a general algorithm in order to study many static and dynamic magnetoelastic properties of a rare-earth metal, with the use of a general Hamiltonian already known in literature. As a specific application ...
  • Carleman embedding and Lyapunov exponents 
    Andrade, Roberto Fernandes Silva (Journal of Mathematical Physics, 1982)
    We investigate the solutions of those autonomous systems with quadratic nonlinearities in a Ndimensional vector space together with the solutions of their first variational equation systems by means of the Carleman embedding. ...
  • Transfer matrix solution of the Ising model on the Koch curve 
    Andrade, Roberto Fernandes Silva; Salinas, S. R. (Journal of physics A: Mathematical and general, 1984)
    A transfer matrix approach is used to calculate the partition function of the Ising model on the Koch curve. In zero magnetic field it is possible to obtain an exact analytic result. In the presence of a field the problem ...
  • Analogy between Landau theory of phase transitions and Lagrangian mechanics 
    Ribeiro Filho, A.; Tilley, D.R.; Žekš, B. (Physics Letters A, 1984)
    It is shown that the definition of a stable point in landau theory is different from that used in mechanics. The implications for numerical work on phase transitions for systems that have a Lffshitz invariant are discussed.
  • Occurrence of secular terms In the Carleman embedding 
    Esperidião, Antônio Sérgio Cavalcante; Andrade, Roberto Fernandes Silva (Journal of Mathematical Physics, 1986)
    Secular terms occur in many perturbative solutions of nonlinear equation systems. In this work, an investigation is made of which cases they may occur in as the result of the application of the linear Carleman embedding ...
  • Equivalence of self-consistency and conservation of energy in the scattering of an electromagnetic wave by a plane of dipoles 
    Keller, W. A.; Urbanski, Marek (Physics Letters A, 1986)
    The scattering of a harmonic electromagnetic plane wave by a plane of induced dipoles has been rigorously treated by means of the Hertz vector. We have shown that only a self-consistent solution, which takes into account ...
  • Probability density function over the Lorenz attractor: An alternative foiinulation 
    Andrade, Roberto Fernandes Silva (Physical Review A, 1986)
    A new method is proposed to evaluate the probability density function p over the Lorenz attractor. The conservation statement within the continuity equation for p is equivalently replaced by the requirement that all elements ...
  • Imaging gas concentration in the field ion microscope: a theoretical analysis 
    Castilho, Caio Mário Castro de; Ktngham, David R. (1988)
    A Boltzmann equation method for calculating the gas concentration in the field ion microscope is proposed. A simple model for the molecule’s bouncing movement is presented. Numerical results are given and the formation of ...
  • Enhanced spin susceptibility in phosphorus-doped silicon 
    Silva, A. Ferreira da (Physical Review B, 1988)
    The influence of the many-valley isotropic effect of the conduction band with a variational Xz dependence on the metal-nonmetal transition of doped semiconductors is investigated further in the calculation of spin ...
  • A generalized Vlasov equation 
    Santana, Ademir Eugênio de; Matos Neto, A.; Vianna, J.D.M. (Physica A: Statistical Mechanics and its Applications, 1989)
    A two-spacial dimension electronic system characterized by a plasma parameter F ~< 1 is analyzed; then, by using a rigorous non-equilibrium statistical mechanical theory, the evolution of distribution function is considered. ...
  • A propagator theory applied to wave mechanics in phase space 
    Santana, Ademir Eugênio de; Matos Neto, A.; Vianna, J. D. M. (International Journal of Theoretical Physics, 1989)
    The fact that the classical Liouville equation can be analyzed as a dynamical equation in Hilbert-Koopman (HK) space is used in order to develop a perturbative method for the wave mechanics in phase space: an explicit ...
  • Photoinjected carrier's acoustic plasma oscillations 
    Esperidião, Antônio Sérgio Cavalcante; Vasconcellos, Aurea R.; Luzzi, Roberto (Solid-State Electronics, 1989)
    Resorting to the Nonequilibrium Statistical Operator Method (NSOM) we calculate the Raman spectrum of the double (electrons and holes) photoinjected plasma in direct-gap polar semiconductors. It allows us to identify four ...