Materials Literature
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The minimum energy pathway leading between the tautomers of tropolone was calculated using molecular orbital (MO) methods. This, with various 1D and 2D cuts of the potential energy surface (PES) topography, reveals the {tunneling skeleton}/{tunneling H atom} mechanism for tautomerization. In the zero-point states the…
We propose a detailed description of the structural and electronic properties of neutral and charged TinO2n+m clusters (n=1–3 and m=0,1), through simulations based on the density functional theory in the local spin density approximation. In all the isomers studied, strongly bound titanyl groups are found. The order of…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTStrong Ferromagnetic and Antiferromagnetic Exchange Coupling between Transition Metals and Coordinated Verdazyl RadicalsRobin G. Hicks, Martin T. Lemaire, Laurence K. Thompson, and Tosha M. BarclayView Author Information Department of Chemistry, University of Victoria…
The treatment of dipole moments (μ), polarizabilities (α), and hyperpolarizabilities (β, γ) in push−pull systems using electric field simulation for the substituents is reanalyzed and tested by comparison with ab initio Hartree−Fock calculations on representative donor−acceptor (D/A) polyenes. Both vibrational and ele…
We calculate the electronic states of Al$_x$Ga$_{1-x}$As/GaAs/Al$_x$Ga$_{1-x}$As double heterojunctions subjected to a magnetic field parallel to the quasi two-dimensional electron gas. We study the energy dispersion curves, the density of states, the electron concentration and the distribution of the electrons in the…
We compare the models that have been proposed in the literature for the atomic structure of the 90-degree partial dislocation in the homopolar semiconductors, silicon, diamond, and germanium. In particular, we examine the traditional single-period and our recently proposed double-period core structures. Ab-initio and…
Carbon and nitrogen austenites, modeled by Fe8N and Fe8C superstructures are studied by full-potential LAPW method. Structure parameters, electronic and magnetic properties as well as hyperfine interaction parameters are obtained. Calculations prove that Fe-C austenite can be successfully modeled by ordered Fe8C super…
The spectroscopic characteristics of systems with adsorbed d impurities on noble metal surfaces should depend on the number and geometric arrangement of the adsorbed atoms and also on their d band filling. Recent experiments using scanning tunneling microscopy have probed the electronic structure of all 3d transition…
In a recent Letter [N. Lehto and S. Oberg, Phys. Rev. Lett. 80, 5568 (1998)], Lehto and Oberg investigated the effects of strain fields on the core structure of the 90-degree partial dislocation in silicon, especially the influence of the choice of supercell periodic boundary conditions in theoretical simulations. We…
We investigate theoretically the spatial dependence of the linear absorption spectra of single and coupled semiconductor quantum dots, where the strong three-dimensional quantum confinement leads to an overall enhancement of Coulomb interaction and, in turn, to a pronounced renormalization of the excitonic properties.…
An analysis of the transport properties data on established thermoelectric materials indicates that the ratio of the electrical power factor to optimum electrical conductivity appears constant. This result, when combined with the previously proposed concept of a minimum thermal conductivity, enables realistic maximum…
This work presents a comparative analysis of the N 1s core level spectra, as measured by x-ray photoelectron spectroscopy (XPS) and x-ray absorption spectroscopy (XAS), of amorphous CNx films which gives evidence of the existing correlation between the different components that constitute the respective spectra. After…
We have investigated magnetic properties of SmNi4B. The material undergoes a ferromagnetic ordering at TC≈39 K, which, surprisingly, is higher than that of isostructural GdNi4B (≈36 K). The saturation magnetic moment is rather small (0.15 μB per Sm at 5 K), suggesting the presence of crystal-field effects. Below TC, t…
The structural, magnetic and transport properties of La 0.5 Ca 0.5 Mn 1- x Sn x O 3 (0⩽ x ⩽0.1) have been investigated systematically. A significant lattice expansion is observed due to the introduction of Sn. With the increase of the Sn content, the Curie temperature ( T C ) decreases sharply in the case of low dopin…
This paper considers a theoretical model of the metal-tunnel interface layer-thin porous silicon-p-Si structure. A diffusion-drift equation at the appropriate boundary conditions is solved to clarify a mechanism of the carriers' transport. The voltage drop distribution along the structure is calculated by solving the…
Recently, Sidebottom [Phys. Rev. Lett. 82, 3653 (1999)] proposed a new scaling approach for the conductivity spectra of ion conducting glasses. This approach is based on the condition that the shape of the spectra is universal. In this Letter, we show that this condition is generally not fulfilled, but that the shape…
We make glass of dilute LiCl aqueous solution by cooling micrometer-sized droplets of the solution extremely quickly and measure the Raman spectra of the glass. It is found that the OH stretching vibration mode of the glass of dilute solution is composed of the OH stretching vibration mode of pure glassy water and tha…
We derive a generalized Drude formula for the optical conductivity of quasicrystals, assuming a diffusion law in a perfect quasicrystal L(t) approximately t(beta), where L(t) measures the spreading of a wave packet in a time t. We show that the so-called Drude peak in the optical conductivity, characteristic of metals…
Temperature dependence of fluorescence spectra of Cr4+ in an aluminate glass in the range of 1.2–1.6 μm was investigated from 15 to 300 K. The emission spectra were broadband centered at about 1.3 μm, wider than 200 nm width. The emission intensity drastically increased with decreasing temperature and that of 15 K was…
We performed first-principle calculations of substitutional sulfur in diamond, in the neutral (S0) and charged states. The energy levels induced by sulfur in diamond are calculated to be 0.15 and 0.5 eV from the bottom of the conduction band, for S0 and the singly ionized state S+, respectively. The formation energy f…