Spin-polarized density functional theory is used to investigate hydrogen-induced magnetism in single-walled carbon nanotubes SWNTs . Hydrogen trapped at a carbon vacancy can trigger delocalized electron spin polarization on semiconducting zigzag SWNTs. Hydrogen pinned by a carbon adatom on the surface of the SWNT can induce spin polarization localized at the carbon adatom, independent of the di...

A hybrid modeling approach combining two-dimensional atomistic molecular dynamics simulations of vacancy formation with a continuum analysis of vacancy diffusion has been used to predict the vacancy content of vapor deposited nickel as a function of deposition rate/temperature and incident flux energy/angle. The hybrid approach uses a previously developed molecular dynamics technique to obtain ...

Point defects and pores in diamond affect its optical and electrical properties. We generated and evaluated a large number of vacancy V(n) clusters representing nanosized voids in diamonds for n up to 65. Our generational algorithm spawns the new generation n + 1 from the list of the most stable structures in the previous generation n. With energy as the only criterion, we generate a large stru...

The mechanisms for the resistance to sulfur poisoning at the triple phase boundary (TPB) of the Ni/yttria-stabilized zirconia (YSZ) system treated with Sn vapor are studied using the first-principles method based on density functional theory. Models with Sn dopant or adsorbate are proposed. It is found that the TPB model of the Ni/YSZ system with Sn dopant in Ni can to some extent restrain the ...

The e ects of impurity atoms as well as various growth methods to the formation of vacancy type defects in gallium nitride (GaN) have been studied by positron annihilation spectroscopy. It is shown that vacancy defects are formed in Ga or N sublattices depending on the doping of the material. Vacancies are decorated with impurity atoms leading to the compensation of the free carriers of the sam...

Atomic-scale calculations indicate that both stress effects and chemical binding contribute to the redistribution of solute in presence vacancy clusters magnesium alloys, leading segregation driven by thermodynamics. As size cluster increases, becomes more important relative stress. These solute–vacancy interactions also impact diffusivity vacancies a solid solution. Simulations show atoms acce...

This Letter discusses inner-shell excitation in collisions of very heavy ions (2, -2, 2 140) in the framework of the quasimolecular model. The importance of multistep excitations and of coupling between continuum states is demonstrated. The lso vacancy probabilities resulting from coupled-channels calculations exceed perturbation theory by a factor 3-5, thus giving good agreement with recent ex...

Cross sections for target atom K vacancy production have been measured recently, using solid targets of Cu, Mo, Ag, Sn, Sm, and Ta bombarded by 10 A MeV beams of H, Ne, Ar, Cr, Kr, Xe, and Bi [1]. It was found that the target K x-ray production cross section becomes enhanced as the target atomic number Z2 approaches the atomic number Z1 of the projectile. The purpose of the work presented here ...

We perform a comparative study of the free energies and the density distributions in hard-sphere crystals using Monte Carlo simulations and density functional theory (employing Fundamental Measure functionals). Using a recently introduced technique [T. Schilling and F. Schmid, J. Chem. Phys. 131, 231102 (2009)] we obtain crystal free energies to a high precision. The free energies from fundamen...

We study the relationship between precipitate morphology and superconductivity in KxFe1.6+ySe2 single crystals grown by self-flux method. Scanning electron microscopy (SEM) measurements revealed that the superconducting phase forms a network in the samples quenched above iron vacancy order-disorder transition temperature Ts, whereas it aggregates into micrometer-sized rectangular bars and align...