Materials Literature
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Molecular dynamics simulations of a Xe monolayer sliding on Ag(001) and Ag(111) are carried out in order to ascertain the microscopic origin of friction. For several values of the electronic contribution to the friction of individual Xe atoms, the intra-overlayer phonon dissipation is calculated as a function of the c…
An astonishingly broad application potential in biotechnology, biomimetics, and nanotechnology is revealed by studies on the structure, chemistry, biosynthesis, genetics, self-assembly, and function of supramolecular surface layers (S layers). These are monomolecular, crystalline assemblies of protein or glycoprotein…
Ab initio molecular orbital calculations have been used to study the effect of γ substituents (X = H, F, or CN) on the addition of 1-Y,3-X-disubstituted propyl radicals (Y = F or CN) to ethylene. It is found that, although the γ substituent (i.e. penultimate unit) can exert a significant effect on the stability of the…
Raman and infrared reflection spectra in the backbone deformations and lattice modes range (10−1000 cm -1 ) of EB/ES-I and EB/ES-II polyanilines are discussed and compared with those of an oligomer (BQBBa) and of the constitutive bricks of the polyaniline skeleton: diphenylamine (BB), N, N ‘-diphenyl-1,4-phenylenediam…
The magnetic exchange interactions in copper(II) &mgr;(2)-azido bridged complexes have been studied using several density functionals and both GTO and STO basis sets. From a methodological point of view, we have taken into proper account nonorthogonality effects in the framework of the broken symmetry approach. A rema…
The effects of a step defect and a random array of point defects (such as vacancies or substitutional impurities) on the force of friction acting on a xenon monolayer film as it slides on a silver (111) substrate are studied by molecular dynamic simulations and compared with the results of lowest order perturbation th…
The electronic structure of a single monatomic gold wire is presented for the first time. It has been obtained with state-of-the-art ab-initio full-potential density-functional (DFT) LMTO (linearized muffin-tin orbital) calculations taking into account relativistic effects. For stretched structures in the experimental…
The FT-IR and FT-Raman spectra of three-layered silicates, magadiite, kenyaite, and ilerite have been measured. The correlation between vibrational spectra and the structural properties of silicates under investigation has been made. The unit cells of all three silicates appear to be centrosymmetric since the mutual e…
A novel procedure has been developed for the synthesis of spongelike silica membranes with three-dimensional meso−macrostructures. The process utilizes multiphase media comprised of a mesoscopically ordered block copolymer/silica phase that macroscopically separates from an electrolyte phase. This results in hierarchi…
Increased interest in molecular time scales below the glass transition temperature, T g, has arisen from the desire to identify the conditions (e.g., temperature) where the molecular processes which lead to unwanted changes in amorphous systems (e.g., chemical reactivity, crystallization, structural collapse) are impr…
Linear arrays of CaF2 stripes and dots, about 7 nm wide, are fabricated by self-assembly on stepped Si(111). Stripes are grown on a CaF1 passivation layer, dots directly on Si. The stripes have a precision of ±1 nm, are continuous, do not touch each other, and are attached to the top of the step edges. The stripe repu…
A rational approach to the problem of accelerated testing of high temperature polymeric composites is discussed. The methods provided are considered tools useful in the screening of new materials systems for long-term application to extreme environments that include elevated temperature, moisture, oxygen, and mechanic…
To understand the dynamics of photoinduced volume expansion (PVE) in amorphous chalcogenides, in situ PVE (time evolution of thickness changes during illumination) measurements have been performed. Two distinct behaviors, transient and metastable PVE, have been observed. A strong correlation between the changes in thi…
Growth behaviors of SrTiO3/LaAlO3 films could be varied substantially by controlling terminating atomic layers of the substrates. In a film on the LaO-terminated substrate, strain-induced roughening was observed. In a film on the AlO2-terminated substrate, the first atomic layer of the interface seemed to have lots of…
We have conducted a comparative study of the strain effect on the anisotropic low-field magnetoresistance (LFMR) in ultrathin Pr0.67Sr0.33MnO3 films epitaxially grown on LaAlO3(LAO), NdGaO3(NGO), and SrTiO3(STO) substrates. Distinctive LFMR effects have been observed on films with compressive (on LAO), tensile (on STO…
Epitaxial thin films of Sr2FeMoO6, that are ordered double perovskite with half-metallic nature, have been successfully prepared on SrTiO3 (001) and (111) substrates by pulsed laser deposition in a narrow window of the temperature and oxygen pressure. From the surface morphology analysis for the atomic scale step-and-…
Electrical contacts to carbon nanotubes typically exhibit high resistance, posing a serious obstacle to their application in electronic devices. One important factor may be their unique electronic structure, which gives weak electronic coupling at the Fermi surface. This suggests some possible ways to reduce contact r…
A brief review of the SIESTA project is presented in the context of linear-scaling density-functional methods for electronic-structure calculations and molecular-dynamics simulations of systems with a large number of atoms. Applications of the method to different systems are reviewed, including carbon nanotubes, gold…
The thermodynamics of the 2D XY model is formulated by a transfer matrix method and analyzed by a density matrix renormalization group. The finite-size scaling and the beta function of the model are studied by the Roomany-Wyld renormalization group theory. It is found that the 2D XY model has an essential finite-size…
We report the observation of large low-field magnetoresistance (MR) behavior in ${\mathrm{CaCu}}_{3}{\mathrm{Mn}}_{4}{\mathrm{O}}_{12}$ with a perovskite-related $({\mathrm{AA}}^{\ensuremath{'}}_{3}B_{4}{\mathrm{O}}_{12})$ structure. ${\mathrm{Ca}}^{2+}{\mathrm{Cu}}_{3}^{2+}{\mathrm{Mn}}_{4}^{4+}{\mathrm{O}}_{12}$ is…