Gloria M. Buendía

Bio: Gloria M. Buendía is an academic researcher from Simón Bolívar University. The author has contributed to research in topics: Ising model & Kinetic Monte Carlo. The author has an hindex of 17, co-authored 64 publications receiving 930 citations. Previous affiliations of Gloria M. Buendía include Florida State University & University of New Mexico.

Numerical study of a mixed Ising ferrimagnetic system

Abstract: We present a study of a classical ferrimagnetic model on a square lattice in which the two interpenetrating square sublattices have spins one-half and one. This model is relevant for understanding bimetallic molecular ferrimagnets that are currently being synthesized by several experimental groups. We perform exact ground-state calculations for the model, and employ Monte Carlo and numerical transfer-matrix techniques to obtain the finite-temperature phase diagram for both the transition and compensation temperatures. When only nearest-neighbour interactions are included, our non-perturbative results indicate no compensation point or tricritical point at finite temperature, which contradicts earlier results obtained with mean-field analysis.

Kinetics of a mixed Ising ferrimagnetic system

Abstract: We present a study, within a mean-field approach, of the kinetics of a classical mixed Ising ferrimagnetic model on a square lattice, in which the two interpenetrating square sublattices have spins $\ensuremath{\sigma}=\ifmmode\pm\else\textpm\fi{}1/2$ and $S=\ifmmode\pm\else\textpm\fi{}1,0.$ The kinetics is described by a Glauber-type stochastic dynamics in the presence of a time-dependent oscillating external field and a crystal field interaction. We can identify two types of solutions: a symmetric one, where the total magnetization $M$ oscillates around zero, and an antisymmetric one where $M$ oscillates around a finite value different from zero. There are regions of the phase space where both solutions coexist. The dynamical transition from one regime to the other can be of first or second order depending on the region in the phase diagram. Depending on the value of the crystal field we found up to two dynamical tricritical points where the transition changes from continuous to discontinuous. Also, we perform a similar study on the Blume-Capel $(S=\ifmmode\pm\else\textpm\fi{}1,0)$ model and find strong differences between its behavior and the one of the mixed model.

Monte Carlo study of a mixed spin-3/2 and spin-1/2 Ising ferrimagnetic model

Abstract: The magnetic properties of a mixed Ising ferrimagnetic model on a square lattice, in which the two interpenetrating square sublattices have spins that can take two values, $\ensuremath{\sigma}=\ifmmode\pm\else\textpm\fi{}1/2,$ alternated with spins that can take four values, $S=\ifmmode\pm\else\textpm\fi{}3/2,\ifmmode\pm\else\textpm\fi{}1/2,$ are studied. This model can be relevant for understanding the magnetic behavior of the new class of organometallic ferrimagnetic materials that exhibit spontaneous magnetic moments at room temperature. We carried out exact ground-state calculations for the model and employ a Monte Carlo algorithm to obtain the finite-temperature phase diagram for both the transition and compensation temperatures. The role of the different interactions in the Hamiltonian is explored. When only the nearest-neighbor interaction and the crystal-field term are included our results indicate no compensation point at finite temperature. When the next-nearest-neighbor interaction between the spins $\ensuremath{\sigma}=\ifmmode\pm\else\textpm\fi{}1/2$ exceeds a minimum value that depends on the other parameters in the Hamiltonian, a compensation point appears. The interaction between the $S=\ifmmode\pm\else\textpm\fi{}3/2$ spins, next-nearest neighbors in the lattice, has the effect of changing the compensation temperature.

Mass media and heterogeneous bounds of confidence in continuous opinion dynamics

Abstract: This work focuses on the effects of an external mass media on continuous opinion dynamics with heterogeneous bounds of confidence. We modified the original Deffuant et al. and Hegselmann and Krause models to incorporate both, an external mass media and a heterogeneous distribution of confidence levels. We analysed two cases, one where only two bounds of confidence are taken into account, and other where each individual of the system has her/his own characteristic level of confidence. We found that, in the absence of mass media, diversity of bounds of confidence can improve the capacity of the systems to reach consensus. We show that the persuasion capacity of the external message is optimal for intermediate levels of heterogeneity. Our simulations also show the existence, for certain parameter values, of a counter-intuitive effect in which the persuasion capacity of the mass media decreases if the mass media intensity is too large. We discuss similarities and differences between the two heterogeneous versions of these continuous opinion dynamic models under the influence of mass media.

Monte Carlo simulation of a mixed spin 2 and spin Ising ferrimagnetic system

Abstract: The critical behaviour of a mixed ferrimagnetic Ising system on a square lattice in which the two interpenetrating square sublattices have spins and has been studied. We carried out exact ground state calculations and performed Monte Carlo simulations to obtain the finite-temperature phase diagram of the model. We found that the system that includes only a nearest-neighbour interaction and the crystal field does not have a compensation point. Also, our study seems to indicate that, contrary to effective-field predictions, there is no tricritical point at nonzero temperature for this model; however a more elaborate analysis will be needed to draw a definite conclusion on this point.

The Physics of Foraging: An Introduction to Random Searches and Biological Encounters

Abstract: Do the movements of animals, including humans, follow patterns that can be described quantitatively by simple laws of motion? If so, then why? These questions have attracted the attention of scientists in many disciplines, and stimulated debates ranging from ecological matters to queries such as 'how can there be free will if one follows a law of motion?' This is the first book on this rapidly evolving subject, introducing random searches and foraging in a way that can be understood by readers without a previous background on the subject. It reviews theory as well as experiment, addresses open problems and perspectives, and discusses applications ranging from the colonization of Madagascar by Austronesians to the diffusion of genetically modified crops. The book will interest physicists working in the field of anomalous diffusion and movement ecology as well as ecologists already familiar with the concepts and methods of statistical physics.

Consensus Reaching in Social Network Group Decision Making: Research Paradigms and Challenges

Abstract: In social network group decision making (SNGDM), the consensus reaching process (CRP) is used to help decision makers with social relationships reach consensus. Many CRP studies have been conducted in SNGDM until now. This paper provides a review of CRPs in SNGDM, and as a result it classifies them into two paradigms: (i) the CRP paradigm based on trust relationships, and (ii) the CRP paradigm based on opinion evolution. Furthermore, identified research challenges are put forward to advance this area of research.