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We calculated the field emission of the W(001) surface based on a local density functional method. In this method, the electronic structure and the potential under an external electric field are calculated self-consistently using the pseudopotential method. The method is easy to implement and requires minimal computation time beyond that of a standard density functional calculation, while at the same time fully compatible with the density functional formalism. Results such as the enhancement factors are in good agreement with experiments and the effect of the surface reconstruction and the choice of exchange-correlation functionals on the field emission current will be discussed. (c) 2005 Elsevier Ltd. All rights reserved.

We calculated the field emission of the W(001) surface based on a local density functional method. In this method, the electronic structure and the potential under an external electric field are calculated self-consistently using the pseudopotential method. The method is easy to implement and requires minimal computation time beyond that of a standard density functional calculation, while at the same time fully compatible with the density functional formalism. Results such as the enhancement factors are in good agreement with experiments and the effect of the surface reconstruction and the choice of exchange-correlation functionals on the field emission current will be discussed. (c) 2005 Elsevier Ltd. All rights reserved.

We calculated the field emission of the W(001) surface based on a local density functional method. In this method, the electronic structure and the potential under an external electric field are calculated self-consistently using the pseudopotential method. The method is easy to implement and requires minimal computation time beyond that of a standard density functional calculation, while at the same time fully compatible with the density functional formalism. Results such as the enhancement factors are in good agreement with experiments and the effect of the surface reconstruction and the choice of exchange-correlation functionals on the field emission current will be discussed. (c) 2005 Elsevier Ltd. All rights reserved.

We applied a simple yet accurate self-consistent method using the density-functional formalism to study the field-emission properties of nanographite ribbons. We found some properties that are unique to nanostructure arrays, including the field-emission current being dominated by the contribution from off-zone-center π states in some of the cases because of specific wave function symmetries, and an anomalous current density dependence on the inter-ribbons separation due to edge dipole effects. The applicability of Fowler-Nordheim analysis and some related problems are also discussed.

Local density functional calculations are used to investigate the structural, cohesive, and magnetic properties of Ni, Co, and Fe on various orientations of the W surface. We found that all these elements wet all the W surface orientations for at least one monolayer so that thermodynamically stable ultrathin coatings of these elements can be formed. However, the magnetic properties are strongly orientation dependent. We will see that thermodynamically stable and ferromagnetic ultrathin coatings with large differences between the majority- and minority-spin density of states near the Fermi level may be realizable for some of these 3d metals on some orientations of the tungsten surface.

Local density functional calculations are used to investigate the structural, cohesive, and magnetic properties of Ni, Co, and Fe on various orientations of the W surface. We found that all these elements wet all the W surface orientations for at least one monolayer so that thermodynamically stable ultrathin coatings of these elements can be formed. However, the magnetic properties are strongly orientation dependent. We will see that thermodynamically stable and ferromagnetic ultrathin coatings with large differences between the majority- and minority-spin density of states near the Fermi level may be realizable for some of these 3d metals on some orientations of the tungsten surface.

Local density functional calculations are used to investigate the structural, cohesive, and magnetic properties of Ni, Co, and Fe on various orientations of the W surface. We found that all these elements wet all the W surface orientations for at least one monolayer so that thermodynamically stable ultrathin coatings of these elements can be formed. However, the magnetic properties are strongly orientation dependent. We will see that thermodynamically stable and ferromagnetic ultrathin coatings with large differences between the majority- and minority-spin density of states near the Fermi level may be realizable for some of these 3d metals on some orientations of the tungsten surface.

The growth morphology, structure, and magnetism of ultrathin Co films on the W(111) surface are studied with conventional and spin polarized low energy electron microscopy and diffraction and first principles total energy calculations. Pseudo-layer-by-layer growth of thick pseudomorphic (ps) Co films is observed at 380 K, while Stranski-Krastanov growth and transformation to a (6×6) closed-packed structure are observed at higher temperatures. On the basis of the calculations, only one ps Co monolayer is expected to be thermodynamically stable against three-dimensional island formation. Calculations also indicate that the magnetic moment on Co atoms at the interface is reduced due to strong hybridization with the substrate, but remains non-zero even for the single ps monolayer. Metastable ps Co/W(111) is found experimentally to be ferromagnetically ordered at 380 K when film thickness exceeds 7.6 ps ML. Although only in-plane magnetization is observed, substrate atomic steps have a strong influence on the magnetization easy axis and magnetic domain structure, which suggests that the in-plane magnetocrystalline anisotropy is weak.

The growth morphology, structure, and magnetism of ultrathin Co films on the W(111) surface are studied with conventional and spin polarized low energy electron microscopy and diffraction and first principles total energy calculations. Pseudo-layer-by-layer growth of thick pseudomorphic (ps) Co films is observed at 380 K, while Stranski-Krastanov growth and transformation to a (6×6) closed-packed structure are observed at higher temperatures. On the basis of the calculations, only one ps Co monolayer is expected to be thermodynamically stable against three-dimensional island formation. Calculations also indicate that the magnetic moment on Co atoms at the interface is reduced due to strong hybridization with the substrate, but remains non-zero even for the single ps monolayer. Metastable ps Co/W(111) is found experimentally to be ferromagnetically ordered at 380 K when film thickness exceeds 7.6 ps ML. Although only in-plane magnetization is observed, substrate atomic steps have a strong influence on the magnetization easy axis and magnetic domain structure, which suggests that the in-plane magnetocrystalline anisotropy is weak.

The growth morphology, structure, and magnetism of ultrathin Co films on the W(111) surface are studied with conventional and spin polarized low energy electron microscopy and diffraction and first principles total energy calculations. Pseudo-layer-by-layer growth of thick pseudomorphic (ps) Co films is observed at 380 K, while Stranski-Krastanov growth and transformation to a (6×6) closed-packed structure are observed at higher temperatures. On the basis of the calculations, only one ps Co monolayer is expected to be thermodynamically stable against three-dimensional island formation. Calculations also indicate that the magnetic moment on Co atoms at the interface is reduced due to strong hybridization with the substrate, but remains non-zero even for the single ps monolayer. Metastable ps Co/W(111) is found experimentally to be ferromagnetically ordered at 380 K when film thickness exceeds 7.6 ps ML. Although only in-plane magnetization is observed, substrate atomic steps have a strong influence on the magnetization easy axis and magnetic domain structure, which suggests that the in-plane magnetocrystalline anisotropy is weak.