نتایج جستجو برای: density functional theoryhalf metals
تعداد نتایج: 1010396 فیلتر نتایج به سال:
WIEN97 is a program package to calculate the electronic structure of solids. The calculations are based on Density Functional Theory. A coarse grain parallelization of the code based on distributing k-points onto diierent processors is not only relatively simple to implement but also very eecient, especially in metals, where a large number of k-points must be calculated. After the development o...
Variations of the photoionization cross section of valence states as a function of interatomic distance are studied by means of atomic and solid-state density functional approaches and compared with photoemission data. In contrast to the free atom case, a series of Cooper minima is found for 4d, 5d, and 5f states in Pd, Ag, Au, and U metals. The discovered fundamental phenomenon is of high impo...
Collective surface excitations in alkali-metal overlayers are observed using photoyield spectroscopy. Spectra for Na and K on Al~111! reveal a multipole surface plasmon and bulklike overlayer plasmon. In contrast, Li on Al exhibits only the multipole mode. In the submonolayer regime, all three alkali metals provide evidence for the threshold excitation. Time-dependent density-functional calcula...
We combine ab initio density functional theory with transport calculations to provide a microscopic basis for distinguishing between good and poor metal contacts to nanotubes. Comparing Ti and Pd as examples of different contact metals, we trace back the observed superiority of Pd to the nature of the metal-nanotube hybridization. Based on large scale Landauer transport calculations, we suggest...
This article reviews the current status of lattice-dynamical calculations in crystals, using density-functional perturbation theory, with emphasis on the plane-wave pseudo-potential method. Several specialized topics are treated, including the implementation for metals, the calculation of the response to macroscopic electric fields and their relevance to long wave-length vibrations in polar mat...
The application of the density-functional theory in the local approximation to magnetic materials is discussed and illustrated by examples. The magnetic properties of the 3d elemental metals as well a s their cohesive properties are described by means of self-consistent local-spin-density (LSD) calculations and by using the LSD-Stoner method. The application of the LSD approximation to narrow-b...
A laboratory experiment was conducted to assess the bioaccumulation of microelements Fe 2+, Cu 2+, Zn 2+ and their effects on the growth and pigment contents of Spirulina platensis in Zarrouk’s media. The mentioned metals concentrations enhanced separately to tenfold of the Zarrouk’s content. The results indicated no differences in the dry weights for the different medias (p>0.05). A rapid incr...
The package fhi96md is an efficient code to perform density-functional theory totalenergy calculations for materials ranging from insulators to transition metals. The package employs first-principles pseudopotentials, and a plane-wave basis-set. For exchange and correlation both the local density and generalized gradient approximations are implemented. The code has a low storage demand and perf...
Atoms and mohxuka adsorbed on metals affect each other even over comiderable dktances. In a , tour-d-force of density-functional methods, we establish the nature and strength of such indirect Y interactions, and explain for what adaorbate systems they can critically &act important materials= ~ properties. These perceptions are verified in kinetic Monte Carlo simulations of epitaxial gr~< ~ and ...
We show that density functional theory calculations have reached an accuracy and speed making it possible to use them in conjunction with an evolutionary algorithm to search for materials with specific properties. The approach is illustrated by finding the most stable four component alloys out of the 192 016 possible fcc and bcc alloys that can be constructed out of 32 different metals. A numbe...
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