Self-consistent Green function approach for calculations of electronic structure in transition metals

We present an approach for self-consistent calculations of the many-body Green function in transition metals. The distinguishing feature of our approach is the use of the one-site approximation and the self-consistent quasiparticle wave function basis set, obtained from the solution of the Schrodinger equation with a nonlocal potential. We analyze several sets of skeleton diagrams as generating functionals for the Green function self-energy, including GW and fluctuating exchange sets. Their relative contribution to the electronic structure in 3d-metals was identified. Calculations for Fe and Ni revealed stronger energy dependence of the effective interaction and self-energy of the d-electrons near the Fermi level compared to s and p electron states. Reasonable agreement with experimental results is obtained

Hybrid applications over XML - integrating the declarative and navigational approaches

We discuss the design of a quasi-statically typed language for XML in which data may be associated with different structures and different algebras in different scopes, whilst preserving identity. In declarative scopes, data are trees and may be queried with the full flexibility associated with XML query algebras. In procedural scopes, data have more conventional structures, such as records and sets, and can be manipulated with the constructs normally found in mainstream languages. For its original form of structural polymorphism, the language offers integrated support for the development of hybrid applications over XML, where data change form to re flct programming expectations and enable their enforcement

Effects of electronic correlation on X-Ray absorption and dichroic spectra at L2,3_{2,3} edge

We present a new theoretical approach to describe X-Ray absorption and Magnetic Circular Dichroism spectra in the presence of e-e correlation. Our approach provides an unified picture to include correlations in both charged and neutral excitations, namely in direct / inversion photoemission where electrons are removed/added, and photo absorption where electrons are promoted from core levels to empty states. We apply this approach to the prototypical case of L$_{2,3}$ edge of 3$d$ transition metals and we show that the inclusion of many body effects in the core level excitations is essential to reproduce, together with satellite structures in core level photoemission, the observed asymmetric line shapes in X-ray absorption and dichroic spectra.Comment: 3 figures, 5 pages, submitted to Phys. Rev.

OpenAIRE guidelines for CRIS managers: supporting interoperability of open research information through established standards

OpenAIRE is the European infrastructure enabling researchers to comply with the European Union requirements for Open Access to research results. OpenAIRE collects metadata from data sources across Europe and beyond and defines interoperability guidelines to assist providers in exposing their information in a way that is compatible with OpenAIRE. This contribution focuses on a specific type of data source, CRIS systems, and the respective OpenAIRE guidelines, based on CERIF XML. A range of issues, spanning different aspects of information representation and exchange, needed to be addressed by the guidelines in order to define a complete solution for interoperability

Economic sustainability of pig slaughtering firms in the production chain of denomination of origin hams in italy

Pork meat in Italy is one of the largest agri-food chains in Italy. In the swine production chain, slaughter plays an important role, because it has an impact on animal welfare, food safety and the sustainability of the agri-food chain. These companies also deal with pigs destined for typical Denomination of Origin products and therefore play an important role in the production chain of typical products and in the field of EU agricultural policy. In this context, the research aims to analyze the economic sustainability of the major pig slaughter firms in Italy, through data analysis of the annual account statement (AAS) on a sample of eight companies analyzed over a ten-year historical series. Financial ratios and margins (FRM) analysis is applied in the research. FRM analysis shows that firms have the largest absorption of financial resources in the net working capital cycle. The research highlights the high incidence of raw materials in companies in the sector. Consequently, the profit margins of the companies in the sample are modest and in some cases are lower than the cost of debt, suggesting a moderate capacity to attract capital. This result appears as a negative signal of the economic sustainability of the companies in the sector. The research, now limited to a small number of large companies, opens a line of research that can be developed by expanding the sample to small and medium-sized enterprises of the chain of Denomination of Origin hams in Italy to suggest improvement interventions, in particular for rural or marginal areas of production

Thermal denaturation of fluctuating finite DNA chains: the role of bending rigidity in bubble nucleation

Statistical DNA models available in the literature are often effective models where the base-pair state only (unbroken or broken) is considered. Because of a decrease by a factor of 30 of the effective bending rigidity of a sequence of broken bonds, or bubble, compared to the double stranded state, the inclusion of the molecular conformational degrees of freedom in a more general mesoscopic model is needed. In this paper we do so by presenting a 1D Ising model, which describes the internal base pair states, coupled to a discrete worm like chain model describing the chain configurations [J. Palmeri, M. Manghi, and N. Destainville, Phys. Rev. Lett. 99, 088103 (2007)]. This coupled model is exactly solved using a transfer matrix technique that presents an analogy with the path integral treatment of a quantum two-state diatomic molecule. When the chain fluctuations are integrated out, the denaturation transition temperature and width emerge naturally as an explicit function of the model parameters of a well defined Hamiltonian, revealing that the transition is driven by the difference in bending (entropy dominated) free energy between bubble and double-stranded segments. The calculated melting curve (fraction of open base pairs) is in good agreement with the experimental melting profile of polydA-polydT. The predicted variation of the mean-square-radius as a function of temperature leads to a coherent novel explanation for the experimentally observed thermal viscosity transition. Finally, the influence of the DNA strand length is studied in detail, underlining the importance of finite size effects, even for DNA made of several thousand base pairs.Comment: Latex, 28 pages pdf, 9 figure

Fluctuation induced interactions between domains in membranes

We study a model lipid bilayer composed of a mixture of two incompatible lipid types which have a natural tendency to segregate in the absence of membrane fluctuations. The membrane is mechanically characterized by a local bending rigidity $\kappa(\phi)$ which varies with the average local lipid composition $\phi$. We show, in the case where $\kappa$ varies weakly with $\phi$, that the effective interaction between lipids of the same type can either be everywhere attractive or can have a repulsive component at intermediate distances greater than the typical lipid size. When this interaction has a repulsive component, it can prevent macro-phase separation and lead to separation in mesophases with a finite domain size. This effect could be relevant to certain experimental and numerical observations of mesoscopic domains in such systems.Comment: 9 pages RevTex, 1 eps figur

Raman signatures of classical and quantum phases in coupled dots: A theoretical prediction

We study electron molecules in realistic vertically coupled quantum dots in a strong magnetic field. Computing the energy spectrum, pair correlation functions, and dynamical form factor as a function of inter-dot coupling via diagonalization of the many-body Hamiltonian, we identify structural transitions between different phases, some of which do not have a classical counterpart. The calculated Raman cross section shows how such phases can be experimentally singled out.Comment: 9 pages, 2 postscript figures, 1 colour postscript figure, Latex 2e, Europhysics Letters style and epsfig macros. Submitted to Europhysics Letter

Interfacial magnetic structure in Fe/NiO(001)

Using nuclear resonant scattering of synchrotron radiation and density functional theory calculations we haveresolved the magnetic properties of the different Fe phases present at the Fe/NiO(001) interface, an epitaxialferromagnetic/antiferromagnetic system. We have detected the presence of an interfacial antiferromagneticFeO-like phase with a significantly increased magnetic moment compared to the case of a sharp interface.Already a few atomic layers above the interface, the Fe atoms have a bulk-like metallic character and the reversalof their magnetization is strongly influenced by the antiferromagnetic layer