Optical properties of dye sensitized TiO2 nanowires from time‐dependent density functional theory

We present a computational study based on time‐dependent density functional theory of the optical absorption spectra of TiO₂ nanowires sensitized with organic dye molecules. We concentrate on catechol and squaraine dyes. For those molecules, we compute adsorption geometries and energies and investigate the optical properties of the combined dye– nanowire system. We find that although the molecules have qualitatively different optical spectra in the gas phase, both lead to an enhancement of the absorption in the visible frequency range when adsorbed on a nanowire.

     

Hard-core bosons on the kagome lattice: valence-bond solids and their quantum melting

Using large scale quantum Monte Carlo simulations and dual vortex theory, we analyze the ground state phase diagram of hard-core bosons on the kagome lattice with nearest-neighbor repulsion. In contrast with the case of a triangular lattice, no supersolid emerges for strong interactions. While a uniform superfluid prevails at half filling, two novel solid phases emerge at densities rho=1/3 and rho=2/3. These solids exhibit an only partial ordering of the bosonic density, allowing for local resonances on a subset of hexagons of the kagome lattice. We provide evidence for a weakly first-order phase transition at the quantum melting point between these solid phases and the superfluid.     

Absorptive corrections to associated production of strange baryon and meson resonances in πp scattering

Absorptive corrections are calculated for the reactionsπ ⁺ p→K ^*+∑⁺(K ^*+ Y ₁ ^*+ ) mediated byK-exchange andπ ⁺p→K⁺ Y ₁ ^*+ withK ^*-exchange. The effect of the finite width of the resonances is included. Numerical results are given for 5 and 8 GeV/c.     

Kanten-kritische graphen mit der zusammenhangszahl 2

A set of vertices of a graph G represents G if each edge of G is incident with at least one vertex of . A graph G is said to be edge-critical if the minimal number of vertices necessary to represent G decreases if any edge of G is omitted. Plummer [5] has given a method to construct an infinite family of edge-critical graphs with connectivity number 2. We use this method to construct a more extensive class of edge-critical graphs with connectivity number 2 and show that all edge-critical graphs with this connectivity number (K₂) can be constructed from smaller edge-critical graphs. Finally we give examples of edge-critical graphs not constructable from smaller ones by this method.     

Syntheses of the chromomycinone side chain from carbohydrate precursors

Appropriate dithiane derivatives of D-threo configuration were prepared starting with D-arabinose and D-galactose, respectively. Their dianions served for nucleophilic additions to model aldehydes, thus comprising syntheses of the complex side chain of chromomycinone. In contrast to former reports a trianion formation of a dithiane-blocked α,β-dihydroxy aldehyde could not be confirmed.     

Subroutinized tape sorting

The drawbacks of large, general tape sorting programs are pointed out, and a sorting subroutine is suggested as a remedy. The fundamental idea is the separation of the logic in tape sorting from the actual manipulation of external tape units by introduction of the concept of an elementary sorting loop. Examples show how common problems in sorting can be solved using the sorting loop concept. A few considerations in the design and implementation of a sorting subroutine are mentioned, and finally a measure of the efficiency of tape sorting methods is proposed.     

Strongly correlated fermions after a quantum quench

Using the adaptive time-dependent density-matrix renormalization group method, we study the time evolution of strongly correlated spinless fermions on a one-dimensional lattice after a sudden change of the interaction strength. For certain parameter values, two different initial states (e.g., metallic and insulating) lead to observables which become indistinguishable after relaxation. We find that the resulting quasistationary state is nonthermal. This result holds for both integrable and nonintegrable variants of the system.     

Some forms of excluded middle for linear orders

The intersection of a linearly ordered set of total subrelations of a total relation with range 2 need not be total, constructively.     

Dynamic evaluation of integrity and the computational content of Krull's lemma

A multiplicative subset of a commutative ring contains the zero element precisely if the set in question meets every prime ideal. While this form of Krull's Lemma takes recourse to transfinite reasoning, it has recently allowed for a crucial reduction to the integral case in Kemper and the third author's novel characterization of the valuative dimension. We present a dynamical solution by which transfinite reasoning can be avoided, and illustrate this constructive method with concrete examples. We further give a combinatorial explanation by relating the Zariski lattice to a certain inductively generated class of finite binary trees. In particular, we make explicit the computational content of Krull's Lemma.