Materials Literature
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Two types of grain boundary sliding are established and investigated during Zn bicrystal deformation: “pure” grain boundary sliding (GBS) which is not associated with intragranular sliding (IS) and GBS which develops simultaneously with IS. Both types of GBS exhibit greatly similar structural peculiarities but under i…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMollusk shell formation: isolation of two organic matrix proteins associated with calcite deposition in the bivalve Mytilus californianusStephen WeinerCite this: Biochemistry 1983, 22, 17, 4139–4145Publication Date (Print):August 16, 1983Publication History Published online1…
Total-configurational-energy calculations have already been very successfully carried out for periodic structures and for isolated molecules, allowing one to study, e.g., crystal structures, reconstructions, and vibrational frequencies. We describe here for the first time a method for calculating the total energy of i…
M r = 150.6, trigonal, P3121 , a = 6.968(8), c = 6 . 4 1 0 ( 4 ) A , V = 2 6 9 . 5 A 3, Z = 3 , D x = 2 . 6 3 g c m -3, ~ , (MoK~t)=0.7107A, p = 20.24cm -1, room temperature, F(000)= 228. Using 286 reflexions with I > 3o(1), including Friedel pairs, one of the two possible enantiomorphous space groups could be rejecte…
We present a systematic density functional approach to the mean field theory of the isotropic–nematic– smectic A transition. We show that our theory is a generalization of the McMillan theory of smectics, and point out that an additional term arises in the free energy which was not present in the earlier work. Our app…
The local-density approximation (LDA) for the exchange-correlation potential underestimates the fundamental energy gaps of insulators by about 40%. When a simplified self-interaction correction (SSIC) is applied to the band structures of Ne and NaCl, vast improvements over LDA are found in the gaps, with little change…
We have carried out a crystallographic study of the spin-Peierls distorted phase (${T}_{c}=17.4$ K) of N-methyl-N-ethyl-morpholinium ditetracyanoquinodimethanide [MEM${(\mathrm{TCNQ})}_{2}$]. Neutron-diffraction data were collected at 6 K from a deuterated sample. At the transition the unit cell axis along the dimeriz…
We introduce a new one-dimensional kinetic Ising model to study the cooperative dynamics of linear chain molecules. Correlation functions for the model are calculated approximately. We discuss the connection between these correlation functions and certain relaxation functions that can be measured by dielectric and dyn…
The energy involved in the relative ordering of the dimerization patterns of neighboring ${(\mathrm{CH})}_{x}$ chains is evaluated with a model where the coupling is due to the interchain hopping of the $\ensuremath{\pi}$ electrons. It is shown that this mechanism favors antiferromagnetic order between neighboring cha…
Mr=393.26, monoclinic, P2 1/ c, a=13.8937 (14), b=9.6258 (7), c=10.9127 (7) Aring, beta=95.66 (1)deg, V=1452.3 (2) Aring 3, T=295K [the cell parameters were determined from the refinement of 39 theta values from a Guinier-Hagg X-ray powder film (Cr Kalpha radiation, lambda=2.28975 Aring, using a CoP 3 standard: a=7.70…
Using the synchrotron-radiation facility at Brookhaven National Laboratory, we have studied the electronic structure of thin hydrogenated amorphous carbon films produced by dc glow discharges of hydrocarbons. Valence-band photoemission measurements on these films yielded information on the occupied valence-band densit…
This paper describes how the Hubbard model in the atomic limit implemented by taking into account molecular vibrations can give a description of mixed valence binuclear systems with both metallic ions simultaneously magnetic. A FeIII (high spin) FeII (high spin) binuclear complex would constitute an example. In such s…
High-resolution time-of-flight measurements of 17-meV He atoms scattered from an Ag(111) surface along the $〈112〉$ and $〈110〉$ azimuths are reported. Most of the spectra reveal two sharp peaks and from their locations dispersion curves have been determined out to the zone boundary. The agreement of the lower-frequency…
A model for the temperature variations of the thermoelectric power (TEP) of acceptor graphite intercalation compounds (GIC's) is presented. At low temperatures, the TEP in GIC's increases monotonically with $T$, then levels off above \ensuremath{\sim}200 K in striking contrast to that of pristine graphite. The diffusi…
ESR measurements have been performed on samples of neutral polypyrrole, polypyrrole-perchlorate, oxygen-doped polypyrrole, and poly($\ensuremath{\beta}$,${\ensuremath{\beta}}^{\ensuremath{'}}$-dimethylpyrrole perchlorate). A narrow Lorentzian line is observed in oxidized, highly conducting films, but no correlation be…
Angle-resolved core-level and valence-band x-ray photoelectron spectroscopy (XPS) data for GaAs(110), Ge(110), and Ge(111) surfaces are analyzed to determine core-level to valence-band maximum binding-energy differences to a precision of the order of the room-temperature thermal energy. A method for markedly improving…
The microscopic mechanisms responsible for both the formation and coupling of magnetic moments in Heusler alloys (${X}_{2}\mathrm{Mn}Y$) are identified. We find that the $X$ atoms (e.g., Cu, Pd) serve primarily to determine the lattice constant, while the $Y$ atoms (e.g., Al, In, Sb) mediate the interaction between th…
Inelastic electron scattering is calculated by means of a simplified model of the generalised oscillator strength density distribution of an atomic or solid target. The parameters of the model are a limited set of resonance energies (partial mean ionisation potentials) and oscillator strengths. Methods to estimate the…
The authors review the use of the ideas of 'ionicity' and 'covalency' in quantitative studies of the solid state. Such ideas have taken several distinct forms: a description of charge distributions of bonding, a spectroscopic classification of perfect solids, and a framework for quantitative modelling of defects in po…
The problem of minimizing the full cholesteric free energy in flat space is difficult since the bending and bulk energies favor different forms of the order parameter. It is shown, however, that the problem can be solved exactly on the surface of a sphere in four-space, where the curvature relieves the strains induced…