Search results for "Tight binding"

Tight-Binding Model for Spontaneous Magnetism of Quantum Dot Lattices

2003

We use a simple tight-binding model to study the magnetism of two-dimensional quantum dot lattices with 1 to 12 electrons per dot. The results show that in the middle of an electron shell the lattice favours antiferromagnetism while with nearly empty or full shells ferromagnetism is favoured. The size of the antiferromagnetic region increases with the coordination number of the dot. A one-dimensional dot lattice shows a spin-Peierls transition. The results for a square lattice are in good agreement with density functional calculations of Koskinen et al.

Tight-binding calculation of spin splittings in semiconductor superlattices

1995

Density-functional based tight-binding study of small gold clusters

2006

In this paper, we report the ability of self-consistent-charge density-functional based tight-binding method to describe small gold clusters. We concentrate our investigations mainly on anions, and find that the method describes their geometric and electronic structures fairly well, in comparison with density-functional calculations. In particular, the method correctly reproduces the planarity of ground-state structures up to cluster sizes in agreement with experiment and density-functional theory.

Effects of the Surface and Finite Temperature on the Electronic Structure of Metal Clusters

1996

The most fascinating feature of simple metal clusters is the existence of the electronic shell structure. This was observed first in alkali[1] and noble metals[2] and later also in some other nontransition metals[3,4,5]. The shell structure is a consequence of nearly free valence electrons confined to a finite volume. A spherical potential will always lead to a shell structure, the origin of which is the orbital angular momentum l and the large degeneracy (2l+1) associated with it. However, this primitive shell structure is strengthened by ’accidental’ degeneracies between states having different principal quantum numbers. Thus the shell structure of a hydrogen atom is different from that o…

Level-spacing distribution in the tight-binding model of fcc clusters.

1993

A lattice-gas Monte Carlo method is used to simulate metallic fcc clusters at finite temperatures. A tight-binding model including s and p electrons has been derived for reproducing the free-electron-like energy band for the bulk metal and this model is used for calculating the electronic structures of the fcc cluster. The resulting level-spacing distribution at the Fermi energy is a Wigner distribution. The width of the distribution in small clusters is smaller than that calculated from the bulk density of states. In the lattice gas clusters the energy gaps related to the electronic magic numbers do not show up at the Fermi level. The energy between the last occupied and the first unoccupi…

Shell structure and level spacing distribution in metallic clusters

1993

The lattice gas Monte Carlo and tight binding method is used to study the electronic shell structure in large metallic clusters. The average density of states of a large ensemble of deformed clusters shows the same shell structure as the most spherical geometry. The level spacing distribution at the Fermi level is a Wigner distribution.

Structure and superconductivity in LnNi2B2C: comparison of calculation and experiment

2001

Abstract The experimental relation between the superconducting transition temperature ( T c ) and lattice size for the lanthanide nickel borocarbides is clarified. The electronic density of states (DOS) at the Fermi energy is calculated by the LMTO method for selected non-magnetic lanthanides. The T c and the DOS are both shown to scale in the same way with a structural parameter that characterizes the bond angle in the NiB 4 tetrahedra. The results strongly support arguments that the suppression of superconductivity on going from smaller to larger lanthanides in the quaternary nickel borocarbides is structurally driven. A structure– T c relationship of this type is unusual for intermetalli…

Correction to “Self-Consistent Charge Density-Functional Tight-Binding Parameterization for Pt–Ru Alloys”

2018

Tight-Binding Simulations of Nanowires

2015

A tight-binding potential for the simulation of solid and liquid iodine

2003

In this work, we suggest an interatomic potential for iodine applicable to the simulation of the condensed phases of the halogen within the temperature and density range accessible to experiments. The potential includes an attractive term that is partitioned into directional chemical bonding with a many-particle character and a pairwise interaction. Despite its simplicity, the potential reproduces the crystal structure of solid iodine, the presence of atomic phases with increasing pressure, and the metallic or insulating character of the solid phases. Finally, we present preliminary simulation results for fluid iodine.