Real-Space Interpretation of Interatomic Charge Transfer and Electron Exchange Effects by Combining Static and Kinetic Potentials and Associated Vector Fields

Intricate behavior of one-electron potentials from the Euler equation for electron density and corresponding gradient force fields in crystals was studied. Bosonic and fermionic quantum potentials were utilized in bonding analysis as descriptors of the localization of electrons and electron pairs. Channels of locally enhanced kinetic potential and the corresponding saddle Lagrange points were found between chemically bonded atoms linked by the bond paths. Superposition of electrostatic φ_es (r) and kinetic φ_k (r) potentials and electron density ρ(r) allowed partitioning any molecules and crystals into atomic ρ- and potential-based φ-basins; the φ_k-basins explicitly account for electron exchange effect, which is missed for φ_es-ones. Phenomena of interatomic charge transfer and related electron exchange were explained in terms of space gaps between ρ- and φ-zero-flux surfaces. The gap between φ_es- and ρ-basins represents the charge transfer, while the gap between φ_k- and ρ-basins is proposed to be a real-space manifestation of sharing the transferred electrons. The position of φ_k-boundary between φ_es- and ρ-ones within an electron occupier atom determines the extent of electron sharing. The stronger an H‧‧‧O hydrogen bond is, the deeper hydrogen atom’s φ_k-basin penetrates oxygen atom’s ρ-basin. For covalent bonds, a φ_k-boundary closely approaches a φ_es-one indicating almost complete sharing the transferred electrons, while for ionic bonds, the same region corresponds to electron pairing within the ρ-basin of an electron occupier atom.

Synthesis of Active Pharmaceutical Ingredients using Electrochemical Methods: Keys to Improve Sustainability

Organic electrochemistry is receiving renewed attention as a green and cost-efficient synthetic technology. Electrochemical methods promote redox transformations by electron exchange between electrodes and species in solution, thus avoiding the...

Vortices in a strongly coupled collisional quantum plasma embedded in an external magnetic field

Vortex motion of a cylindrical quantum plasma containing degenerate inertialess electrons and strongly correlated, non-degenerate inertial ions is studied. The electron exchange–correlation and ion–neutral collisional effects are taken into consideration, along with vertical external magnetic field and radial electric field. Considering generalized viscoelastic momentum equation for strongly coupled ions in quasi-crystalline state, variation of different rotational characteristics along radial distance are discussed numerically. Existence of shear rotation is observed near both the core and the periphery of the vortex, which is found to be modified by ion–ion correlation, quantum effects of the degenerate electrons, the ion–neutral collision, as well as by the magnetic field. It is noticed that electron exchange–correlation potential and quantum diffraction play major roles in modifying the rotational characteristics. Vorticity and the rate of increment of enstrophy with respect to radial distance, diminish to zero towards the periphery of the vortex. Also, it is noted that the ion–neutral collision may be responsible for reducing the increment of enstrophy.

The Effect of Unparticle in the Processes \(e^{+}e^{-}\rightarrow \gamma \gamma\) and \(\gamma e^{-}\rightarrow U^{\mu }e^{-}\) when the \(e^{+},e^{-}\) Beams Are Polarized in Unparticle Physics

We investigate the influence of unparticle physics on the positron-electron collider via the scalar unparticle and electron exchange. From computing the contribution of the unparticle exchange to the cross-section (CS) as well as evaluating the dependence of differential cross-section (DCS) on the scattering angle , we calculate the production of vector unparticle in the photon-electron collider in s- and t- channels such as missing energy distribution. Besides, we also found that the polarization of the beams also significantly contributes to the CS and DCS of the unparticle production.

Positronium Confined in Nanocavities: The Role of Electron Exchange Correlations

Positronium atoms (Ps) are commonly employed as a probe to characterize nanometric or subnanometric voids or vacancies in nonmetallic materials, where Ps can end up confined. The annihilation lifetime of a trapped Ps is strongly modified by pickoff and depends on the cavity size and on the electron density in the confining cavity surface. Here, we develop a theory of the Ps annihilation in nanocavities based on the fundamental role of the exchange correlations between the Ps-electron and the outer electrons, which are not usually considered but must be considered to correctly theorize the pickoff annihilation processes. We obtain an important relation connecting the two relevant annihilation rates (for the p-Psand the o-Ps) with the electron density, which has the property of being totally independent of the geometrical characteristics of the nanoporous medium. This general relation can be used to gather information on the electron density and on the average cavity radius of the confining medium, starting from the experimental data on PALS annihilation spectra. Moreover, by analyzing our results, we also highlight that a reliable interpretation of the PALS spectra can only be obtained if the rule of 1/3 between the intensities of p-Psand o-Pslifetimes can be fulfilled.