Search results for "Exchange"
showing 10 items of 2035 documents
Insight Into The Spin-Vibronic Problem of a Mixed Valence Magnetic Molecular Cell for Quantum Cellular Automata.
2021
The effects of the vibronic coupling in quantum cellular automata (QCA) based on the square planar mixed valence (MV) molecular cells comprising four paramagnetic centers (spin cores) and two excess mobile electrons are analyzed in the important particular case when the Coulomb energy gap between the ground antipodal diagonal-type two-electron configurations and the excited side-type configurations considerably exceeds both the one-electron transfer parameter (strong U-limit) and the vibronic stabilization energy. Under such conditions the developed model involves the second-order double exchange, the Heisenberg-Dirac-Van Vleck (HDVV) exchange and the vibronic coupling of the excess electro…
Electrically switchable magnetic exchange in the vibronic model of linear mixed valence triferrocenium complex
2018
In this article, we report our development of a vibronic model for the electric-field control of antiferromagnetic superexchange in the mixed-valence (MV) triferrocenium complex FeIII-FeII-FeIII proposed as a possible candidate for the molecular implementation of a quantum logic gate. Along with the electronic interactions, such as electron transfer between the iron ions in different oxidation degrees and Coulomb repulsion of the extra holes, the proposed model of the triferrocenium complex also takes into account the vibronic coupling as an inherent ingredient of the problem of mixed valency. The latter is described by the conventional Piepho-Krauzs-Shatz (PKS) model adapted to the linear …
Isovector spin-multipole strength distributions in double- β -decay triplets
2017
In this work the energetics and strength distributions of isovector spin-dipole and spin-quadrupole transitions from the ground states of the pairs ($^{76}\mathrm{Ge}, ^{76}\mathrm{Se}$), ($^{82}\mathrm{Se}, ^{82}\mathrm{Kr}$), ($^{96}\mathrm{Zr}, ^{96}\mathrm{Mo}$), ($^{100}\mathrm{Mo}, ^{100}\mathrm{Ru}$), ($^{116}\mathrm{Cd}, ^{116}\mathrm{Sn}$), ($^{128}\mathrm{Te}, ^{128}\mathrm{Xe}$), ($^{130}\mathrm{Te}, ^{130}\mathrm{Xe}$), and ($^{136}\mathrm{Xe}, ^{136}\mathrm{Ba}$), of double-$\ensuremath{\beta}$-decay initial and final nuclei, to the ${J}^{\ensuremath{\pi}}={0}^{\ensuremath{-}},{1}^{\ensuremath{-}},{2}^{\ensuremath{-}},{1}^{+},{2}^{+}$, and ${3}^{+}$ excited states of the interm…
The calculation of the mean radiant temperature of a subject exposed to the solar radiation – A generalised algorithm
2005
Abstract The thermal sensation experienced by a subject in a confined environment is significantly affected by the radiative heat exchange between the human body and the surrounding surfaces: it contributes as far as 30% of the whole thermal exchanges of the subject. Besides, the presence of high-intensity radiation sources like, for example, the sun, may appreciably modify the radiant field to which people are exposed. As a consequence, this could alter notably the comfort conditions. In order of properly taking into account this issue, a simple analytical method is introduced in this work, that allows the easy evaluation of the thermal radiant field induced by the presence of the solar ra…
Recent results on heavy-ion direct reactions of interest for 0νββ decay at INFN - LNS
2020
Abstract Neutrinoless double beta decay of nuclei, if observed, would have important implications on fundamental physics. In particular it would give access to the effective neutrino mass. In order to extract such information from 0νββ decay half-life measurements, the knowledge of the Nuclear Matrix Elements (NME) is of utmost importance. In this context the NUMEN and the NURE projects aim to extract information on the NME by measuring cross sections of Double Charge Exchange reactions in selected systems which are expected to spontaneously decay via 0νββ. In this work an overview of the experimental challenges that NUMEN is facing in order to perform the experiments with accelerated beams…
Magnetic Exchange between Orbitally Degenerate Ions: A New Development for the Effective Hamiltonian
1998
A new approach to the problem of the kinetic exchange for orbitally degenerate ions is developed. The constituent multielectron metal ions are assumed to be octahedrally coordinated, and strong crystal field scheme is employed, making it possible to take full advantage from the symmetry properties of the fermionic operators and collective electronic states. In the framework of the microscopic approach, the highly anisotropic effective Hamiltonian of the kinetic exchange is constructed in terms of spin operators and standard orbital operators (matrices of the unit cubic irreducible tensors). As distinguished from previous considerations, the effective Hamiltonian is derived for a most genera…
Exchange Interactions II: Spin Hamiltonians
1996
In Part I the physical mechanism of exchange interactions have been discussed. In this part we introduce the general concept of spin-hamiltonian. Isotropic exchange hamiltonian for many-electron polynuclear clusters (Heisenberg-Dirac-van Vleck-HDVV model [1-6]) will be derived. Spin-hamiltonian approach allows to separate the full exchange problem into two independent ones: 1) evaluation of the energy levels of the exchange system considering Jij as a set of semiempirical parameters, and 2) quantum mechanical calculation of exchange parameters with the aim of elucidation of the main physical mechanisms of the exchange coupling. In this part we shall focus on the problem of calculation of sp…
A Numerical Approach to Study Shell-Side Fluid Flow in Shell-and-Tube Heat Exchangers
2022
Abstract The detailed CFD simulation of the shell-side flow inside shell-and-tube heat exchangers results prohibitive for large-size components, due to the large number of tubes, together with the multi-scale nature of the flow features. To overcome this issue, the porous media approach can be adopted, substituting the tube bundle with a porous domain, where a suitable momentum sink term in the Navier-Stokes equation is provided. In this paper, a novel numerical approach to estimate the crossflow shell-side pressure drop is presented: a complete characterization of the tube bundle was performed by running 2D-CFD steady-state isothermal analyses, collecting pressure gradient magnitudes and d…
Similarities and singularities of three DnaK proteins from the cyanobacterium Synechocystis sp. PCC 6803.
2010
In the genome of completely sequenced mesophilic cyanobacterium Synechocystis sp. PCC 6803 three DnaK proteins are encoded, which share a high degree of sequence identity in their N-terminal ATPase region as well as in the adjacent peptide-binding domain. However, as typical for DnaK proteins, the C-termini of the three Synechocystis proteins are highly diverse. To study the functions of the three Synechocystis DnaK proteins in more detail, we have analyzed the abundance of the individual proteins in Synechocystis cells as well as dnaK expression under various stress conditions. The presented results show that all three Synechocystis DnaK proteins interact with the same GrpE nucleotide exch…
Note esplorative in tema di dissesto delle piattaforme di scambio e deposito di criptovalute
2021
Il lavoro si occupa dei dissesti delle piattaforme digitali di scambio e deposito di criptovalute (crypto-exchanges) e tenta di individuare, nell'ordinamento italiano, le norme applicabili.