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Spin-orbit and relativistic effects on structures and stabilities of group 17 fluorides EF3 (E = I, At, and element 117): Relativity induced stability for the D-3h structure of (117)F-3
No full textSpin-orbit and scalar relativistic effects on geometries, vibrational frequencies, and energies for group 17 fluorides EF3 (E = 1, At, and element 117) are evaluated with two-component methods using relativistic pseudopotentials and effective one-electron spin-orbit operators. The inclusion of relativistic effects makes the D-3h structure of (I 17)F-3 a stable local minimum, whereas IF3 and AtF3 retain C-2nu local minima even with relativistic effects. The valence shell electron pair repulsion model is not appropriate to explain the molecular structure of (I 17)F-3. The geometries of EF3 (E = 1, At, and element 117) molecules are optimized at the HF level with and without spin-orbit effects. Spin-orbit interactions elongate the bond lengths and decrease the harmonic vibrational frequencies. In the case of AtF3, spin-orbit interactions increase the bond lengths by 0.044 and 0.023 Angstrom for r(e)(eq) and r(e)(ax), respectively. Spin-orbit effects widen the bond angle of C-2nu structures of re re IF3 and AtF3, i.e., spin-orbit effects diminish the second-order Jahn-Teller term. The bond angle alpha(e) of AtF3 increases by 3.9degrees due to spin-orbit interactions in addition to the increase of 4.8degrees by scalar relativistic effects. For (I 17)F-3, spin-orbit effects increase the bond length by 0.109 Angstrom. The spin-orbit interactions stabilize (I 17)F-3 by a significant margin (similar to1.2 eV). This stabilization of the molecule compared with open p-shell atoms is quite unusual. Enhanced ionic bonding may be responsible for this stabilization because the electronegative F atom can effectively polarize or attract electrons from the destabilized 7(P3/2) spinors of element 117 due to huge spin-orbit splitting of 7p
QUANTITATIVE-ANALYSIS ON SWELLING BEHAVIOR OF HSMA PVA IPN IONIC GELS UNDER ELECTRIC-FIELD
No full textIn order to explain the electric response of HSMA/PVA IPN ionic gel, polyion concentration (f) and/or interaction parameter (chi(ij)) between gel and water are used, which were previously determined elsewhere by comparing swelling behaviours in the mixed solvents with Tanaka's theory [1]. Ionic polymer gel separated from the electrodes exhibits exponential responses when the electric field is applied or stopped, where the characteristic times for swelling and shrinking and equilibrium swelling ratio are successfully correlated with polyion concentration or interaction parameter. In addition, the strength of field is also an important factor to determine the overall responses. The direction of gel with respect to the electric field is also considered and optimum size was apparent to show maximum swelling
QUANTITATIVE-ANALYSIS ON SWELLING BEHAVIOR OF IONIC GELS IN THE MIXED-SOLVENTS
No full textPhase transition was observed in HSMA/PVA IPN gels having ionizable groups with 3-dimensional network structure in the mixed solvents such as water-methanol, water-acetone or water-ethanol. In order to analyze this phenomena quantitatively, two adjustable parameters related to gel properties were determined from the model based on Tanaka theory. One was the number of dissociated counterions per effective chain (f), the other was the interaction parameters (chi(ij)) between gel and water. As increasing the composition of water, swelling of the gels occurs in the mixed solvent; the gel was shrunk instead when the water content was decreased, which was reversible regardless of the path of swelling and shrinking. A degree of swelling or shrinking of the gel was dependent upon these chi(ij) and f of the gel. With smaller chi(ij) and larger f, more rapid phase transition was observed. Additionally, swelling and shrinking behavior of the gel in system of two solvents and one polymer was influenced not only by chi(ij) between gel and solvents but also by chi(ij) between two solvents
Effects of the magnetic part of the Breit term on bonding: Model calculations with small diatomic molecules
No full textModel calculations for small molecules Li-2, F-2, LiF and BF have been performed at the Dirac-Fock level of theory using Dirac-Coulomb and Dirac-Coulomb-Magnetic Hamiltonians with various basis sets. In order to understand what may happen when the relativity becomes significant, the value of c, speed of light, is varied from the true value of 137.036 a.u. to 10(5) (nonrelativistic case) and also to 50 and 20 a.u. (exaggerated relativistic cases). Qualitative trends are discussed with special emphasis on the effect of the magnetic part of the Breit interaction term. The known relativistic effects on bonding such as the bond length contraction or expansion are demonstrated in dris model study. Total energy, pi -orbital splitting, bond length, bond dissociation energy and dipole moment are calculated, and shown to be modified in a uniform direction by the effect of the magnetic term. Inclusion of the magnetic term raises the total energy, increases the bond length, reduces the pi -orbital splitting, increases the bond dissociation energy, and mitigates the changes in dipole moment caused by the Dirac term
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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