Energija osnovnog stanja u proširenom 2D Hubbardovom modelu za konačan sustav s egzaktnom dijagonalizacijom

Using an exact analytical diagonalization for an extended Hubbard model, we study the first nearest-neighbour repulsion effect on the behaviour of a two-dimensional system of finite size at low density of electrons. The obtained results show that the introduction of the nearest-neighbour off-site interaction allows the correlation effects to become more remarkable and to play an essential role in the electron dynamics, and this off-site interaction encourages the formation of double occupancies.Primjenom egzaktne analitičke dijagonalizacije za proširen Hubbardov model proučavamo učinak odbojne sile među prvim susjedima na svojstva konačnog dvodimenzijskog sustava pri niskim gustoćama elektrona. Postignuti ishodi pokazuju da uvođenje prvo-susjedskog međudjelovanja izvan sustava omogućuje pojačanje korelacijskih učinaka, igra bitnu ulogu u dinamici elektrona, te to međudjelovanje izvan sustava podstiče stvaranje dvostrukih popunjenja

Recent Progress in Advanced Materials for Photonics and Energy Applications

préambule de cette édition : ua12808</p

Study of surface diffusion by Langevin Dynamics simulation

We investigate the dynamic properties of Brownian interacting particles subject to a two-dimensional periodic potential. By employing the Langevin dynamics simulation, we calculate the collective diffusion coefficient in different situations corresponding to different densities. On the other hand, our numerical studies show that the collective diffusion coefficient depends not only on the shape of adsorbed potential but also on the coupling between particles.We investigate the dynamic properties of Brownian interacting particles subject to a two-dimensional periodic potential. By employing the Langevin dynamics simulation, we calculate the collective diffusion coefficient in different situations corresponding to different densities. On the other hand, our numerical studies show that the collective diffusion coefficient depends not only on the shape of adsorbed potential but also on the coupling between particles

Surface diffusion in the framework of lattice gas model: mean field treatment and Monte-Carlo method

We have studied the lattice gas model subject to nearest neighbour repulsive interactions with the Monte-Carlo method leading to a clear understanding of order-disorder transition and its effect on the adsorption and intercalation processes. The lattice division into two (three) sublattices in the case of the square (triangular) lattice enables us to underline the appearance and the growth of the ordered phase. A comparison between the mean field approximation and Monte-Carlo results is also presented.We have studied the lattice gas model subject to nearest neighbour repulsive interactions with the Monte-Carlo method leading to a clear understanding of order-disorder transition and its effect on the adsorption and intercalation processes. The lattice division into two (three) sublattices in the case of the square (triangular) lattice enables us to underline the appearance and the growth of the ordered phase. A comparison between the mean field approximation and Monte-Carlo results is also presented

The growth dynamics of the wedding-cake Interfaces

In the limit where the ratio of the surfaces diffusion coefficient to the deposition rate D/F ∞ → , the surface consists of wedding-cake structures. In order to understand the growth dynamics and the scaling properties of theses interfaces, we have calculated the time evolution of its width ω(L,t) for both one and two dimensional lattice. By the use of the dynamic scaling approach, we find that ω(L,t) scales with time t and length L as ω(L,t)≈Lα f(t/Lα/β ) where f is a scaling function and α and β are respectively the roughening and the growth exponents. The values of theses exponents are in good agreement with the theoritical ones predicted by the Edwards-Wilkinson equation.In the limit where the ratio of the surfaces diffusion coefficient to the deposition rate D/F ∞ → , the surface consists of wedding-cake structures. In order to understand the growth dynamics and the scaling properties of theses interfaces, we have calculated the time evolution of its width ω(L,t) for both one and two dimensional lattice. By the use of the dynamic scaling approach, we find that ω(L,t) scales with time t and length L as ω(L,t)≈Lα f(t/Lα/β ) where f is a scaling function and α and β are respectively the roughening and the growth exponents. The values of theses exponents are in good agreement with the theoritical ones predicted by the Edwards-Wilkinson equation