Materials Literature
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We investigate the electronic structure of ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{VO}}_{3}$ for various values of x. ${\mathrm{LaVO}}_{3}$ is a Mott-Hubbard insulator with band gap of about $1.0\ifmmode\pm\else\textpm\fi{}0.2\mathrm{eV}.$ Hole doping in this system leads to the growth of a new feat…
A study was made on the effects of polymerization conditions on the long-chain branching, molecular weight, and end-group types of polyethene produced with the metallocene-catalyst systems Et[Ind]2ZrCl2/MAO, Et[IndH4]2ZrCl2/MAO, and (n-BuCp)2ZrCl2/MAO. Long-chain branching in the polyethenes, as measured by dynamic rh…
The electronic structure and bonding of ${\mathrm{Gd}}_{3}{\mathrm{Sc}}_{2}{\mathrm{Ga}}_{3}{\mathrm{O}}_{12}$ (GSGG), ${\mathrm{Gd}}_{3}{\mathrm{Sc}}_{2}{\mathrm{Al}}_{3}{\mathrm{O}}_{12}$ (GSAG), and ${\mathrm{Gd}}_{3}{\mathrm{Ga}}_{5}{\mathrm{O}}_{12}$ (GGG) crystals with a garnet structure are studied by means of…
The electronic structure of ${\mathrm{InGaZnO}}_{4},$ which has a layered structure with alternating laminated layers of ${\mathrm{InO}}_{2}$ and ${\mathrm{GaZnO}}_{2},$ was calculated in order to investigate the mechanism of electrical conductivity. In the crystal structure obtained through relaxation calculations us…
Amorphous FeCoB alloys can have high resistivity and relatively high saturation magnetization which are desired for ultrahigh frequency devices such as future write heads and wireless inductors. In this study, FeCoB films are observed to have a low easy axis coercivity (1–2 Oe), a field deposited induced anisotropy of…
We have performed dc transport and optical conductivity measurements on purified and potassium doped thick films of single walled carbon nanotubes. The pristine sample is characterized by a metallic (Drude) response of the optical properties despite the non-metallic behavior in the dc resistivity measurements. Even th…
Extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) were used to investigate the local structure of Pd supported on ZSM-5, which was affected by the acid sites of support and the adsorption of nitrogen oxide. After the thermal treatment of the initially ion-exchanged Pd am…
Analytical second derivatives for combined QM/MM calculations have been formulated and implemented in the CHARMM program interfaced with the ab initio quantum mechanical GAMESS and CADPAC programs. This makes possible evaluation of vibrational frequencies and infrared intensities in large systems that cannot be treate…
The atomic structure of a carbon nanotube can be described by its chiral angle and diameter and can be specified by a pair of lattice indices $(n,m).$ The electronic and mechanical properties are critically dependent on these indices. Scanning tunneling microscopy (STM) is a useful tool to investigate carbon nanotubes…
We combine a density functional theory (DFT) with a self-consistent field model (SCF) to calculate the phase behavior of thin, oblate colloidal particles that are coated with surfactants and dispersed in a polymer melt. These coated particles represent organically modified clay sheets. By integrating the two methods,…
The structure of amorphous carbon at densities of 2.0, 2.6, 2.9, and 3.2 ${\mathrm{g}/\mathrm{c}\mathrm{m}}^{3}$ has been investigated using Car-Parrinello ab initio molecular dynamics. The networks were generated by rapidly cooling samples of 125 atoms to form a solid amorphous structure. The important structural att…
The authors have shown accelerated endothelialization on polyethylene terephthalate (PET) grafts preclotted with autologous bone marrow. Bone marrow cells have a subset of early progenitor cells that express the CD34 antigen on their surfaces. A recent in vitro study has shown that CD34(+) cells can differentiate into…
Second electron affinities of Au_N and Ag_N clusters and the dissociation energies for fission of the Au_N^{2-} and Ag_N^{2-} dianions are calculated using the finite-temperature shell-correction method and allowing for triaxial deformations. Dianionic clusters with N > 2 are found to be energetically stable against f…
Excitonic spectra are calculated for free-standing, surface passivated, InAs quantum dots using atomic pseudopotentials for the single-particle states and screened Coulomb interactions for the two-body terms. We present an analysis of the single particle states involved in each excitation in terms of their angular mom…
A convenient method for the systematic introduction of a variety of organoimido ligands at terminal oxo sites in the hexamolybdate cluster [Bu 4 N] 2 [Mo 6 O 19 ] is described, consisting of reaction with the appropriate organic isocyanate RNCO (R = n -butyl, cyclohexyl, 2,6-diisopropylphenyl) in pyridine solution. Si…
Polycrystalline samples of the strongly distorted $R{\mathrm{NiO}}_{3}(R=\mathrm{H}\mathrm{o},\mathrm{}\mathrm{Y},\mathrm{}\mathrm{E}\mathrm{r},\mathrm{}\mathrm{T}\mathrm{m},\mathrm{}\mathrm{Y}\mathrm{b},\mathrm{}\mathrm{Lu})$ perovskites have been prepared under high hydrostatic pressure, at 20 kbar. The crystal stru…
Crystallographic data, electrical and thermal transport measurements, and heat-capacity data are reported for several compounds with the filled skutterudite structure: ${\mathrm{Tl}}_{x}{\mathrm{Co}}_{4\ensuremath{-}y}{\mathrm{Fe}}_{y}{\mathrm{Sb}}_{12}$ and ${\mathrm{Tl}}_{x}{\mathrm{Co}}_{4}{\mathrm{Sb}}_{12\ensurem…
We investigate the thermal conductivity of bulk silicon crystals based on molecular-dynamics (MD) simulations. If it is taken that the system size must be larger than the phonon mean free path, several hundreds of millions of atoms must be computed for crystals with large thermal conductivity values such as Si. We dem…
Analytical expressions for the velocities of the longitudinal and the torsional sound waves in single-walled carbon nanotubes are derived using Born's perturbation technique within a lattice-dynamical model. These expressions are compared to the formulas for the velocities of the sound waves in an elastic hollow cylin…
A study of thermal conductivities perpendicular to the interfaces in ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}{/\mathrm{S}\mathrm{b}}_{2}{\mathrm{Te}}_{3}$ superlattices is presented. The lattice thermal conductivities in these short-period superlattices are less than those in homogeneous solid-solution alloys and exhibit a…