Formalism With Values
Mostrando 13-24 de 27 artigos, teses e dissertações.
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13. Cálculos de primeiros princípios para BaO.
In this work we present first principles calculations with Density Functional Theory, DFT, using norm-conserving pseudopotentials. Initially, we perform calculations of structural properties for metallic barium, Ba, in the Local Density Approximation, LDA, and Generalized Gradient Approximation, GGA, for the exchange and correlation potential. This study aim
Publicado em: 2005
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14. VIDRO DE SPIN E ANTIFERROMAGNETISMO COM INTERACÃO DE PAREAMENTO BCS LOCAL
In this work the competition among spin glass(SG), antiferromagnetism (AF) and BCS pairs formation (PAIR) in real space is investigated. The model consists of an Ising spin glass term and a local BCS term that favors double site occupation. This model is composed by two sublattices, but only spins in diferent sublattices can interact. The Ising coupling is a
Publicado em: 2005
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15. Novos desenvolvimentos e aplicaÃÃes de mÃtodos de quÃmica quÃntica para compostos de coordenaÃÃo com Ãons lantanÃdeos
Theoretical studies on lanthanide compounds were performed, and divided into three parts: (i) generalization of the Linderberg-Seamans equations for an s-p-d-f basis set; (ii) study of the ligand-to-lanthanide ion charge transfer transitions (LMCT) with the ZINDO98 program using the INDO/S semiempirical hamiltonian and (iii) a study of point charge and charg
Publicado em: 2003
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16. Semiflexible polymer in a strip
We study the thermodynamic properties of a semiexible polymer confined inside strips of widths L <= 9 defined on a square lattice. The polymer is modeled as a self-avoiding walk and a short-range interaction between the monomers and the walls is included through an energy associated with each monomer placed on one
Brazilian Journal of Physics. Publicado em: 2002-12
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17. The Trouble with Diffusion
The phenomenological formalism, which yields Fick's Laws for diffusion in single phase multicomponent systems, is widely accepted as the basis for the mathematical description of diffusion. This paper focuses on problems associated with this formalism. This mode of description of the process is cumbersome, defining as it does matrices of interdiffusion coeff
Materials Research. Publicado em: 2002-09
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18. Physics in the Global Monopole Spacetime
In this paper we review some important aspects of the global monopole spacetime and present how this manifold modifies, at classical and quantum points of view, the movement of a charged particle. The explicit calculations of the renormalized vacuum expectation values of the energy-momentum tensors, áTmn(x)<
Brazilian Journal of Physics. Publicado em: 2001-06
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19. Estabilidade e caos ao redor de centros de atração deformados em gravitação
The behavior of test particles around a multipole deformed attraction center is studied. We find chaotic motions of particles in the field modeled by a monopolar plus a prolate quadrupole term for certain values of parameters. The general relativistic analogous is also studied by using the geodesic formalism in a geometry that represents a monopole (Schwarzc
Publicado em: 2001
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20. Projeto de catalisadores para reações com gas de sintese
A partir do gás de síntese (que constitui uma mistura gasosa de óxidos de carbono e hidrogênio), pode-se obter hidrocarbonetos, álcoois e aldeídos. Estes podem ser obtidos também através da via petroquímica. Portanto, a produção desses compostos a partir do gás de síntese constituem vias alternativas que podem ser exploradas em função de aspec
Publicado em: 2001
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21. Entropia vibracional em ligas metalicas
The thermodynamics properties of alloys are calculated employing the method of Adiabatic Switching in the Molecular Dynamics (MD) formalism. We study the application of the Adiabatic Switching to investigate order-disorder phenomena and point defects in Ni3Al. The MD simulations were performed using the Massive Nosé-Hoover Chain (MNHC) and Andersen dynamics
Publicado em: 1999
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22. Asymmetry and external noise-induced free energy transduction.
The effect of fluctuations in rate constants on the kinetic behavior of cyclic reacting systems, caused by a fluctuating external parameter, is studied. It is shown (i) that the stochastic properties of the system can be analyzed analytically by using the usual master equation approach when the external parameter is fluctuating with discrete square pulses an
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23. Cell sorting is analogous to phase ordering in fluids
Morphogenetic processes, like sorting or spreading of tissues, characterize early embryonic development. An analogy between viscoelastic fluids and certain properties of embryonic tissues helps interpret these phenomena. The values of tissue-specific surface tensions are consistent with the equilibrium configurations that the Differential Adhesion Hypothesis
The National Academy of Sciences.
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24. Simulation of photochemical hole-burning experiments on photosynthetic reaction centers
An effective Hamiltonian formalism is used to calculate the homogeneous linewidth of long-wavelength absorption in the photosynthetic reaction center. Agreement with the experimental values of ≈400 cm-1 for the hole width of the 990-nm band of Rhodopseudomonas viridis is obtained. The anomalously (two orders of magnitude) large width is explained in terms