نتایج جستجو برای: local density approximation

تعداد نتایج: 1080868  

In this study, the optical and magnetic properties of compounds in hexagonal and orthorhombic phases are investigated. The calculations have been carried out in the framework of the functional density theory with various approximations such as local density approximation, Generalized gradient approximation with the pseudopotential and stationary load method, and using the quantum-espresso compu...

1999
A. van de Walle G. Ceder

We introduce a semiempirical method to correct the systematic equilibrium lattice parameters underestimation present in first principles calculations based on the local density approximation. The method consists in performing calculations under a negative pressure such that the calculated equilibrium volume matches the experimentally observed one. We find that elastic properties obtained under ...

Graphite oxide constitutes carbon network with oxygen atoms both on hexagonal arrangement and the edge sites. Structural and electronic properties for graphite-oxygen complexes have been explored using first-principles total-energy calculations within the local density approximation (LDA). Band structures and density of states for the propose carbon 3D models are reported. A finite energy gap and...

The high pressure behavior of the structural and electronic properties of KC1 is studied with use of the density functional pseudopotential method within local-density approximation. Atzero pressure, the rocksalt phase is found to be lower in energy than CsCl structure. However, we predict a phase transition into CsCI structure at a pressure of about 1.5 GPa. The calculated ground state pro...

In this work we use density functional theory based on the ultra-soft pseudo-potential to calculate thestructural, mechanical and thermal properties of narrow single walled BN, AlN and GaN nanotubes.The electron-electron interactions were expressed within the local density approximation (LDA). Wehave also obtained the Phonon dispersion and elastic constants of these nanotubes using the densityf...

2009
L. Chioncel

While the Local Density Approximation LDA+U method is well established for Mott insualtors with well localized orbitals, its application to weakly correlated metals is questionable. By extending the Stoner approach to LDA+U, we show that LDA+U enhances the Stoner factor, while reducing the density of states. The most important correlation effects in metals, fluctuation induced mass renormalizat...

آصف پور, محمدتقی, صاحب سرا, پیمان,

In this paper, we used green's function approach in microscopic theory to investigate a resonant tunneling diode (RTD). We introduced the detailed Hamiltonian for each part of the photovoltaic p-i-n system, then by calculating the green's function components in tight-binding approximation, we calculate local density of states and current-voltage characteristic of the p-i-n structure. Our result...

Graphite oxide constitutes carbon network with oxygen atoms both on hexagonal arrangement and the edge sites. Structural and electronic properties for graphite-oxygen complexes have been explored using first-principles total-energy calculations within the local density approximation (LDA). Band structures and density of states for the propose carbon 3D models are reported. A finite energy gap and...

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