Materials Literature
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An extended Thomas--Fermi--von Weizsacker theory is used to investigate the properties of simple metal surfaces. Fundamental surface quantities such as the work function and surface energy are found to compare quite favorably with the corresponding results obtained through the use of density-functional theory. Applica…
We use a perturbative density matrix treatment to investigate the behavior of the static polarizabilities α of linear conjugated chains CNHN+2, with respect to the chain length and to the presence of neutral and charged conjugation defects of soliton and polaron type. The molecules are described by the Pariser–Parr–Po…
The static structure factor g(k) of the concentrated solution of stiff polymers is calculated based on the generalized random phase approximation (RPA) which accounts for the nematic interaction (i.e., the interaction causing the nematic phase of stiff polymers) between the segments. The structure factor is obtained i…
We report observation of microcrystalline interface phases at the ${\mathrm{SiO}}_{2}$-Si(001) interface. The crystallites have varying degrees of orientational order with respect to the substrate depending on preparation techniques. Most of the diffraction peaks from these phases can be indexed as due to the \ensurem…
We use a perturbative density matrix treatment to investigate the behavior of the first and second static hyperpolarizabilities of linear conjugated chains CNHN+2 described by a Pariser–Parr–Pople Hamiltonian. We examine the evolution of the hyperpolarizabilities with increasing chain lengths, and the effect of differ…
The absorption spectrum of Dy3+:LaCl3 at 4 K has been photographed and measured from 20 000 to 38 000 cm−1. Based on this and previous data, an empirical energy level scheme consisting of 151 observed crystal levels from 0 to 34 130 cm−1 has been determined for the 4f9 ground configuration of trivalent dysprosium in L…
GaSe β 2H cristallise dans le systeme hexagonal avec le groupe d'espace P6 3 /mmc. Affinement de la structure jusqu'a 0,054. La structure est isotypique avec celle de GaS β
The crystal structure of β-CuI at 400°C has been refined from powder crystal X-ray diffraction data. The crystal belongs to the trigonal system with the space group C 1 3v -P3m1, and has lattice constants of a =4.279±0.002 A, c =7.168±0.007 A. The low temperature phase of solid electrolytes is often of tetrahedral str…
Neutron irradiation of ${\mathrm{MgAl}}_{2}$${\mathrm{O}}_{4}$ spinel crystals produces an F-center absorption band in the uv accompanied by a broad absorption band in the visible region. Excitation and emission experiments identify the observed structure in the visible absorption band as optical transitions of transi…
A molecular-dynamics study of the structure and dynamics of monatomic liquids and glasses is presented. The local atomic structure and its development during the quenching process are analyzed in terms of fluctuations of atomic-level stresses and their correlations. This approach extends the basis for the description…
The electronic structures of polyparaphenylene (PPP), polyacetylene (PA), and their derivatives with small energy gaps have been studied by the Hückel and MNDO crystal orbital methods. The effect of nuclear relaxation and heteroatomic substitution on the energy gaps (Eg) have been taken into account by compelete geome…
Eigenstates with an energy E=2 are analyzed for a tight-binding Schr\"odinger equation -${\mathcal{J}}_{〈j}$,i〉${\mathrm{\ensuremath{\psi}}}_{\mathrm{j}}$=E${\mathrm{\ensuremath{\psi}}}_{\mathrm{i}}$ on a two-dimensional Penrose lattice. Two different kinds of eigenstates exist. One is strictly localized and the other…
Stoichiometric amorphous films of InSb or GaSb are found to have very short (< 15 ns) crystallization times when heated to temperatures close to their melting point. They can be used for write-once amorphous to crystalline optical recording. By adding Te to InSb the crystallization time can be tuned so that erasable c…
The glass forming molecular liquid ortho-terphenyl has been investigated by 2H-NMR techniques providing spin-relaxation times (T1, T2), and spin-alignment data which yield information on the time scale and geometry of ultra-slow molecular reorientation. The main results are as follows: The primary glass transition (α…
A field theory, presented earlier by us, which is formally an exact mathematical solution of the Flory–Huggins lattice model, is used to evaluate corrections to Flory–Huggins mean field theory in a systematic series expansion in the inverse of the lattice coordination number and in the nearest-neighbor interaction ene…
We have determined the equilibrium geometry and electronic structure of the compound, ${\mathrm{BC}}_{3}$ using the ab initio pseudopotential local orbital approach and the local-density functional formalism. The boron-carbon compound, ${\mathrm{BC}}_{3}$, is a layered material with gra- phitic structure, where every…
A total-electron-yield technique is described in which near-surface extended x-ray-absorption fine-structure (EXAFS) data are obtained from direct measurements of specimen current. Experiments with several model systems---amorphous germanium and crystalline germanium, nickel, and cobalt; and arsenic ion implanted into…
We prepared Ag-glass composites by impregnating porous glass with a ${\mathrm{AgNO}}_{3}$ solution. The samples were then reduced (in a hydrogen atmosphere) and densified before they were characterized by x-ray diffraction and electron microscopy. The growth of the metal particles inside the glass was studied by a tra…
Hardness and softness kernels η(r,r′) and s(r,r′) are defined for the ground state of an atomic or molecular electronic system, and the previously defined local hardness and softness η(r) and s(r) and global hardness and softness η and S are obtained from them. The physical meaning of s(r), as a charge capacitance, is…
Starting from a description of a molecular wave function using bond orbitals a general formula was derived describing the change of an expectation value of a one electron operator with bond polarization. This equation leads to a bond additive scheme for the description of bond polarization effects containing matrix el…