Finite-Temperature Properties across the Charge Ordering Transition -- Combined Bosonization, Renormalization Group, and Numerical Methods

We theoretically describe the charge ordering (CO) metal-insulator transition based on a quasi-one-dimensional extended Hubbard model, and investigate the finite temperature ($T$) properties across the transition temperature, $T_{\rm CO}$. In order to calculate $T$ dependence of physical quantities such as the spin susceptibility and the electrical resistivity, both above and below $T_{\rm CO}$, a theoretical scheme is developed which combines analytical methods with numerical calculations. We take advantage of the renormalization group equations derived from the effective bosonized Hamiltonian, where Lanczos exact diagonalization data are chosen as initial parameters, while the CO order parameter at finite-$T$ is determined by quantum Monte Carlo simulations. The results show that the spin susceptibility does not show a steep singularity at $T_{\rm CO}$, and it slightly increases compared to the case without CO because of the suppression of the spin velocity. In contrast, the resistivity exhibits a sudden increase at $T_{\rm CO}$, below which a characteristic $T$ dependence is observed. We also compare our results with experiments on molecular conductors as well as transition metal oxides showing CO.Comment: 9 pages, 8 figure

New Trends in Beverage Packaging Systems: A Review

New trends in beverage packaging are focusing on the structure modification of packaging materials and the development of new active and/or intelligent systems, which can interact with the product or its environment, improving the conservation of beverages, such as wine, juice or beer, customer acceptability, and food security. In this paper, the main nutritional and organoleptic degradation processes of beverages, such as oxidative degradation or changes in the aromatic profiles, which influence their color and volatile composition are summarized. Finally, the description of the current situation of beverage packaging materials and new possible, emerging strategies to overcome some of the pending issues are discussed

La liaison halogène [Halogen bonding]

National audienceHalogen bonding, by analogy with hydrogen bonding, describes an intermolecular interaction where an activated halogen atom acts as electrophile through its s-hole area toward a Lewis base. This paper describes its main characteristics and its involvement in many domains, such as crystal engineering, polymers and gels, biomolecular systems or organocatalysis. © 2018 Societe Francaise de Chimie. All rights reserved

The salt-co-crystal continuum in halogen-bonded systems

International audience[No abstract available

Chalcogen bonding in crystalline diselenides and selenocyanates: From molecules of pharmaceutical interest to conducting materials

International audienceOrganic diselenides are nowadays investigated for pharmaceutical applications, as well as in material science in molecular (semi)conductors. In both application's domains, their interactions with Lewis bases, in solution or in the solid state, has been shown to play a crucial role in their biological activity or in their electronic structure. The current comprehensive survey of reported crystal structures of organic diselenides demonstrates the recurrent setting of intermolecular as well as intramolecular chalcogen bonding interactions (ChB) between the selenium atoms acting as ChB donors and Lewis bases. These interactions take place along the two covalent bonds of the selenium atom. In diselenides, stronger interactions are found in the prolongation of the Se[sbnd]Se bond than in the prolongation of the C[sbnd]Se bond. Charge activation of ChB is demonstrated in dicationic diselenides or in cation radical salts of 1,2-diselenole derivatives. This survey is extended to the structures of organic selenocyanates whose crystal structures reflect also the presence of two σ-holes, with a much stronger one in the prolongation of the NC[sbnd]Se bond. Such ChB interactions of selenocyanates with polytopic Lewis bases or with halide anions open novel strategies in crystal engineering and anion recognition strategies