Interplay of matrix element, self-energy and geometric effects in various spectroscopies of the cuprates

We discuss a comprehensive scheme for modeling various highly resolved spectroscopies of the cuprates where effects of matrix element, crystal structure, strong electron correlations, and superconductivity are included realistically in material-specific detail. A number of illustrative examples drawn from our recent work are presented. Specific issues in the cuprate physics considered are: (i) Origin of high-energy kink or the waterfall effect; (ii) Dichroic effects in angle-resolved photoemission spectrum; (iii) Asymmetry of the scanning tunneling spectrum between the processes of electron extraction and injection; (iv) Persistence of ‘Mott’ like high-energy features with doping in optical spectra; (v) Magnetic excitations in electron and hole doped cuprates.     

Experimental observation of strongly bound dimers of sulfuric acid: application to nucleation in the atmosphere

Sulfuric acid is a key compound in atmospheric nucleation. Here we report on the observation of a close-to-collision-limited sulfuric acid dimer formation in atmospherically relevant laboratory conditions in the absence of measurable quantities of ammonia or organics. The observed dimer formation rate was clearly higher than the measured new particle formation rate at ～1.5 nm suggesting that the rate limiting step for the nucleation takes place after the dimerization step. The quantum chemical calculations suggested that even in the ultraclean conditions there exist (a) stabilizing compound(s) with (a) concentration(s) high enough to prevent the dimer evaporation. Such a stabilizing compound should be abundant enough in any natural environment and would therefore not limit the formation of sulfuric acid dimers in the atmosphere.     

Finite-element implementation for electron transport in nanostructures

We have modeled transport properties of nanostructures using Green's-function method within the framework of the density-functional theory. The scheme is computationally demanding, so numerical methods have to be chosen carefully. A typical solution to the numerical burden is to use a special basis-function set, which is tailored to the problem in question, for example, the atomic-orbital basis. In this paper we present our solution to the problem. We have used the finite-element method with a hierarchical high-order polynomial basis, the so-called p elements. This method allows the discretation error to be controlled in a systematic way. The p elements work so efficiently that they can be used to solve interesting nanosystems described by nonlocal pseudopotentials. We demonstrate the potential of the implementation with two different systems. As a test system a simple Na-atom chain between two leads is modeled and the results are compared with several previous calculations. Secondly, we consider a thin hafnium dioxide (HfO2) layer on a silicon surface as a model for a gate structure of the next generation of microelectronics.     

About generalized ideals in a distributive lattice

Let L be a distributive lattice characterized by a ternary operation (, ,), where (a,b,c)=(ab)(bc)(ac)=(ab)(ac)(bc), a,b,cL. The note considers convex sublattices of L, called generalized ideals of L generated by the operation (, ,). Some remarks have been stated about the graph of a distributive lattice.     

Closed set characterizations of finite lattices

Semimodularity and the Jordan-Hölder chain condition are characterized in a finite latticeL by means of special closed sets ofL.     

Screening of light impurities in simple metals

The Kohn-Sham density functional method is used to calculate self-consistent electron densities around H, He and Li impurities in jellium host corresponding to Li, Al and Mg metals. The differences in the density profiles for interstitial and substitutional impurities are investigated. Residual resistivities, relaxation energies and charge transfer in dilute alloys are evaluated.     

Intermolecular bond length of ice on Ag(111)

Water adsorbed in submonolayer coverage on Ag(111) at 70 K forms hydrogen-bonded networks. High resolution images in combination with calculation reveal that single protrusions represent a cyclic water hexamer with the intermolecular bond stretched to the silver lattice constant of 0.29 nm. Scanning tunneling spectroscopy indicates that the bond length within the two-dimensional hydrogen-bonded water layer is shortened. The spectra contain further information about the vibrational modes of water molecules.     

Isomer spectroscopy in (216)(90)Th(126) and the magicity of (218)(92)U(126)

Excited states in (216)Th were investigated via prompt and delayed gamma decays and the recoil-decay tagging method. The decay schemes of the I(pi) = (8+), t(1/2) = 128(8) micros, the I(pi) = (11-), t(1/2) = 615(55) ns, and the I(pi) = (14+), t(1/2) > or = 130 ns isomers were established. The configuration pi h(9/2)f(7/2) is assigned to the I(pi) = (8+) isomer, which implies that the h(9/2) and f(7/2) states are nearly degenerate. This is ascribed to increased binding of the f(7/2) orbital by its coupling to a low-lying I(pi) = (3-) state at E(x) = 1687 keV. The role of octupole and pairing correlations for a Z = 92 shell closure prediction is discussed on the basis of shell model calculations.     

Isomeric states in proton-unbound 187, 189Bi isotopes

Prompt and delayed gamma-ray spectroscopy of very neutron-deficient bismuth isotopes ^{187, 189}Bi has been performed using the Recoil Decay Tagging (RTD) method. The isomeric i _13/2 states have been identified and their lifetimes have been measured. The systematics of these long-lived M2 isomers has been extended to the proton-unbound isotopes. The general behaviour of single-proton states is discussed within the systematics and interpreted within the shell-model framework. Received: 2 May 2002 / Accepted: 3 June 2002 / Published online: 19 November 2002 RID="a" ID="a"e-mail: wkorten@cea.fr RID="b" ID="b"Present address: GANIL, Caen, France. RID="c" ID="c"Present address: Radiation and Nuclear Safety Authority, P.O. Box 14, FIN-00881 Helsinki. Communicated by D. Schwalm