16 documents found, page 1 of 2
A smooth path to plot hydrogen atom via Monte Carlo method.
Lobo, Pedro Henrique Fernandes; Arashiro, Everaldo; Silva, Alcides Volpato Carneiro de Castro e; Pinheiro, Carlos Felipe SaraivaIn this paper, we show how to build a basic computer program using the Monte Carlo method to display the hydrogen atomic orbitals. For this, in a heuristic way, we applied a von Neumann acceptance-rejection method in simple problems of potential wells, and we end with the hydrogen orbitals representation. In this technique, we spread points uniformly on the 1D and 2D charts of probability density distributions,...
An alternative order parameter for the 4-state Potts model.
Fernandes, Henrique Almeida; Arashiro, Everaldo; Felício, José Roberto Drugowich de; Caparica, Álvaro de AlmeidaWe have investigated the dynamic critical behavior of the two-dimensional 4-state Potts model using an alternative order parameter first used by Vanderzande [J. Phys. A 20 (1987) L549] in the study of the Z(5) model. We have estimated the global persistence exponent θg by following the time evolution of the probability P(t) that the considered order parameter does not change its sign up to time t. We have also ...
Short-time dynamics of helix-coil transition in polypeptides
Arashiro, Everaldo; Felício, José Roberto Drugowich de; Hansmann, Ulrich H. E.We study the critical relaxation of the helix-coil transition in all-atom models of polyalanine chains. We show that at the critical temperature the decay of a completely helical conformation can be described by scaling relations that allow us estimating the pertinent critical exponents. The present approach opens a new way for characterizing transitions in proteins and may lead to a better understanding of the...
The stochastic nature of predator prey cycles.
Castro, Tânia Tomé Martins de; Rodrigues, Áttila Leães; Arashiro, Everaldo; Oliveira, Mário José deWe study by numerical simulations the time correlation function of a stochastic lattice model describing the dynamics of coexistence of two interacting biological species that present time cycles in the number of species individuals. Its asymptotic behavior is shown to decrease in time as a sinusoidal exponential function from which we extract the dominant eigenvalue of the evolution operator related to the sto...
Pseudocapacitive behavior of Ti/RhOx+Co3O4 electrodes in acidic medium : applic...
Souza, Adriana Rodrigues de; Arashiro, Everaldo; Golveia, Helder; Lassali, Tânia Aparecida FariasMixtures of RhOx+Co3O4 have been electrochemically studied by cyclic voltammetry in acid solution as a function of composition. The electrodes were prepared by thermal decomposition at 400 °C of mixtures of nitrate precursors. Their electrochemical behavior shows substantial dependence on the electrode’s composition. The Co site controls the electrochemical behavior of the system in the 5–10 mol.% Rh compositio...
A comparative study of the dynamic critical behavior of the four-state Potts li...
Arashiro, Everaldo; Fernandes, Henrique Almeida; Felício, José Roberto Drugowich deWe investigate the short-time critical dynamics of the Baxter–Wu (BW) and n=3 Turban (3TU) models to estimate their global persistence exponent θg. We conclude that this new dynamical exponent can be useful in detecting differences between the critical behavior of these models which are very difficult to obtain in usual simulations. In addition, we estimate again the dynamical exponents of the four-state Potts ...
Short-time critical dynamics of the Baxter-Wu model
Arashiro, Everaldo; Felício, José Roberto Drugowich deWe study the early time behavior of the Baxter-Wu model, an Ising model with three-spin interactions on a triangular lattice. Our estimates for the dynamic exponent z are compatible with results recently obtained for two models which belong to the same universality class of the Baxter-Wu model: the two-dimensional four-state Potts model and the Ising model with three-spin interactions in one direction. However,...
Time correlation function in systems with two coexisting biological species.
Arashiro, Everaldo; Rodrigues, Áttila Leães; Oliveira, Mário José de; Castro, Tânia Tomé Martins deWe study a stochastic lattice model describing the dynamics of coexistence of two interacting biological species. The model comprehends the local processes of birth, death, and diffusion of individuals of each species and is grounded on interaction of the predator-prey type. The species coexistence can be of two types: With self-sustained coupled time oscillations of population densities and without oscillation...
Melanin-like units concentration effects in melanin-like/vanadium pentoxide hyb...
Arashiro, Everaldo; Zampronio, Elaine Cabrini; Brunello, Carlos Alberto; Lassali, Tânia Aparecida Farias; Oliveira, Herenilton PaulinoAn intercalated material has been prepared consisting of a regular alternation of organic/inorganic layers. The films were obtained by reacting 3,4-dihydroxy-phenylalanine (dl-DOPA) with varying concentrations in a solution with freshly prepared HVO3, which suffered a oxidative polymerization/intercalation ‘in situ’ process, forming a green suspension, in which after de-hydration at room temperature produces a ...
Voltammetric characterization of an iridium oxide-based system : the pseudocapa...
Grupioni, Andrea Alves Ferreira; Arashiro, Everaldo; Lassali, Tânia Aparecida FariasMixtures of IrO2+MnO2 (30:70 mol%) have been electrochemically studied by cyclic voltammetry (CV) in acid solution. The crystalline structure, morphology and the electrochemical properties of the electrodes have been studied as a function of the annealing temperature. X-ray diffraction analysis (XRD), show absence of Mn2O3 phase formation and suggest the possible of formation of a solid solution of IrO2 and MnO...