Viet-Duc Ngo

Learn More
By using the Wang-Landau flat-histogram Monte Carlo (MC) method for very large lattice sizes never simulated before, we show that the phase transition in the frustrated Heisenberg stacked triangular antiferromagnet is of first order, contrary to results of earlier MC simulations using old-fashioned methods. Our result lends support to the conclusion of a(More)
We propose a simple model for DNA denaturation bases on the pendulum model of Englander [Proc. Natl. Acad. Sci. U.S.A. 77, 7222 (1980)] and the microscopic model of Peyrard and Bishop [Phys. Rev. Lett. 62, 2755 (1989)], so-called "combined model." The main parameters of our model are the coupling constant k along each strand, the mean stretching y* of the(More)
We study the nature of the phase transition in the fully frustrated simple cubic lattice with the XY spin model. This system is the Villain's model generalized in three dimensions. The ground state is very particular with a 12-fold degeneracy. Previous studies have shown unusual critical properties. With the powerful Wang-Landau flat-histogram Monte Carlo(More)
We show in this paper the results of the phase transition of the so-called fully frustrated simple cubic lattice with the Ising spin model. We use here the Monte Carlo method with the flat energy-histogram Wang-Landau technique which is very powerful for detecting weak first-order phase transition. We show that the phase transition is clearly of first(More)
Visible and near-infrared spectroscopy provides a variety of information regarding leafy vegetables. However, various factors including optical propagation, environmental issues, and experimental issues affect the quality of spectral measurements. Therefore, stability and performance of optical reflectance sensors are affected significantly by sampling(More)
The nature of the phase transition in a system of self-propelling particles has been extensively studied during the past few decades. A theoretical model was proposed by [T. Vicsek et al. Phys. Rev. Lett. 75, 1226 (1995)PRLTAO0031-900710.1103/PhysRevLett.75.1226] with a simple rule for updating the direction of motion of each particle. Based on the model of(More)
In the bulk state, the Ising face-centered-cubic (fcc) antiferromagnet is fully frustrated and is known to have a very strong first-order transition. In this paper, we study the nature of this phase transition in the case of a thin film as a function of the film thickness. Using Monte Carlo simulations, we show that the transition remains first order down(More)
  • 1