Charge Densities of the Nuclei 2O5Tl, 206,208Pb and the Occupancies of the Shell States

1998 ◽  
Vol 07 (03) ◽  
pp. 367-377
Author(s):  
I. S. Gul'karov ◽  
B. P. Nigam
Keyword(s):  
Charge Density ◽  
Shell Model ◽  
Degrees Of Freedom ◽  
Outer Region ◽  
Model Calculations ◽  
Fractional Number ◽  
Charge Densities ◽  
A Charge ◽  
Inner Region

The charge densities of the nuclei 205Tl, 206,208Pb have been calculated in modified shell model with fractional number occupations of the shell states 2s, 2p, 2d, and 3s. The value of the n3 s was found to be 0.6 for 206TI, and ≈ 1 for 206,208Pb. These values differ appreciably from other data which range between 1.3 to 1.6. By addition of the two neutrons to 206P a charge of 0.24e of one proton is moved from the inner region of the 208Pb to the outer region. In the context of our modified shell model calculations, the measured charge density and occupancy profiles imply that the neutron degrees of freedom we employ carry charge.

scholarly journals Probing the interplay between lattice dynamics and short-range magnetic correlations in CuGeO3 with femtosecond RIXS

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
E. Paris ◽  
C. W. Nicholson ◽  
S. Johnston ◽  
Y. Tseng ◽  
M. Rumo ◽  
...  
Keyword(s):  
Short Range ◽  
Degrees Of Freedom ◽  
Time Resolved ◽  
Model Calculations ◽  
Spin Correlations ◽  
Singlet Exciton ◽  
Magnetic Correlations ◽  
Local Lattice ◽  
Frustrated Systems ◽  
A Charge

AbstractInvestigations of magnetically ordered phases on the femtosecond timescale have provided significant insights into the influence of charge and lattice degrees of freedom on the magnetic sub-system. However, short-range magnetic correlations occurring in the absence of long-range order, for example in spin-frustrated systems, are inaccessible to many ultrafast techniques. Here, we show how time-resolved resonant inelastic X-ray scattering (trRIXS) is capable of probing such short-ranged magnetic dynamics in a charge-transfer insulator through the detection of a Zhang–Rice singlet exciton. Utilizing trRIXS measurements at the O K-edge, and in combination with model calculations, we probe the short-range spin correlations in the frustrated spin chain material CuGeO3 following photo-excitation, revealing a strong coupling between the local lattice and spin sub-systems.

scholarly journals Functional implications of the three-dimensional architecture of the rat renal inner medulla

2010 ◽  
Vol 298 (4) ◽  
pp. F973-F987 ◽  
Author(s):  
Anita T. Layton ◽  
Thomas L. Pannabecker ◽  
William H. Dantzler ◽  
Harold E. Layton
Keyword(s):  
Collecting Duct ◽  
Three Dimensional ◽  
Outer Region ◽  
Free Water ◽  
Model Calculations ◽  
Concentrating Mechanism ◽  
Vasa Recta ◽  
Renal Inner Medulla ◽  
Inner Region ◽  
Surprising Finding

A new, region-based mathematical model of the urine concentrating mechanism of the rat renal inner medulla (IM) was used to investigate the significance of transport and structural properties revealed in recent studies that employed immunohistochemical methods combined with three-dimensional computerized reconstruction. The model simulates preferential interactions among tubules and vessels by representing two concentric regions. The inner region, which represents a collecting duct (CD) cluster, contains CDs, some ascending thin limbs (ATLs), and some ascending vasa recta; the outer region, which represents the intercluster region, contains descending thin limbs, descending vasa recta, remaining ATLs, and additional ascending vasa recta. In the upper portion of the IM, the model predicts that interstitial Na+ and urea concentrations (and osmolality) in the CD clusters differ significantly from those in the intercluster regions: model calculations predict that those CD clusters have higher urea concentrations than the intercluster regions, a finding that is consistent with a concentrating mechanism that depends principally on the mixing of NaCl from ATLs and urea from CDs. In the lower IM, the model predicts that limited or nearly zero water permeability in descending thin limb segments will increase concentrating effectiveness by increasing the rate of solute-free water absorption. The model predicts that high urea permeabilities in the upper portions of ATLs and increased contact areas of longest loop bends with CDs both modestly increase concentrating capability. A surprising finding is that the concentrating capability of this region-based model falls short of the capability of a model IM that has radially homogeneous interstitial fluid at each level but is otherwise analogous to the region-based model.

scholarly journals Anharmonic motionsversusdynamic disorder at the Mg ion from the charge densities in pyrope (Mg3Al2Si3O12) crystals at 30 K: six of one, half a dozen of the other

2017 ◽  
Vol 73 (4) ◽  
pp. 722-736 ◽  
Author(s):  
Riccardo Destro ◽  
Riccardo Ruffo ◽  
Pietro Roversi ◽  
Raffaella Soave ◽  
Laura Loconte ◽  
...  
Keyword(s):  
Charge Density ◽  
Low Temperatures ◽  
Degrees Of Freedom ◽  
Phonon Modes ◽  
Dynamic Disorder ◽  
Charge Densities ◽  
Atomic Displacements ◽  
Maximum Resolution ◽  
Full Analysis ◽  
Experimental Findings

The possible occurrence of static/dynamic disorder at the Mg site in pyrope (Mg3Al2Si3O12), with or without anharmonic contribution to the thermal vibrations even at low temperatures, has been largely debated but conclusions were contrasting. Here a report is given on the experimental charge density distribution, ρEXP, of synthetic pyrope atT= 30 K, built through a Stewart multipolar expansion up tol= 5 and based on a very precise and accurate set of in-home measured single-crystal X-ray diffraction amplitudes with a maximum resolution of 0.44 Å. Local and integral topological properties of ρEXPare in substantial agreement with those of ρTHEO, the corresponding DFT-grade quantum charge density of an ideal pyrope crystal, and those derived from synchrotron investigations of chemical bonding in olivines. Relevant thermal atomic displacements, probably anharmonic in nature, clearly affect the whole structure down to 30 K. No significant (> 2.5σ) residual Fourier peaks are detectable from the ρEXPdistribution around Mg, after least-squares refinement of a multipole model with anharmonic thermal motion at the Mg site. Experimental findings were confirmed by a full analysis of normal vibration modes of the DFT-optimized structure of the perfect pyrope crystal. Mg undergoes wide displacements from its equilibrium position even at very low temperatures, as it is allocated in a ∼ 4.5 Å large dodecahedral cavity and involved in several soft phonon modes. Implications on the interplay among static/dynamic disorder of Mg and lattice vibrational degrees of freedom are discussed.

Experimental charge density study on FLPs and a FLP reaction product

2018 ◽  
Vol 233 (9-10) ◽  
pp. 723-731
Author(s):  
Christian Joseph Schürmann ◽  
Regine Herbst-Irmer ◽  
Thorsten Lennart Teuteberg ◽  
Daniel Kratzert ◽  
Gerhard Erker ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Charge Density ◽  
Theoretical Calculations ◽  
X Ray Diffraction ◽  
Charge Density Distribution ◽  
X Ray ◽  
Charge Densities ◽  
A Charge ◽  
Density Study ◽  
Experimental Charge Density

Abstract The charge density distribution of the intramolecular frustrated Lewis pair (FLP) Mes2PCH2CH2B(C6F5)2 (1), the phosphinimine HNPMes2CH2CH2B(C6F5)2 (2), as well as a FLP homologue with nitrogen NEt2CHPhCH2B(C6F5)2 (3) were investigated with Bader’s quantum theory of atoms in molecules (QTAIM). The charge densities were derived from both experimental high-resolution X-ray diffraction data (2, 3) and theoretical calculations (1, 3). The QTAIM analysis for the FLPs 1 and 3 showed the prominent B-pnictogen interaction to be weak dative bonds without significant charge-transfer. This holds also true for the B–N–bond of 2. The nitrogen atom is negatively charged, due to a charge transfer from phosphorous and shows features of a sp2-hybridization. The bond is therefore best described as a non-hypervalent Pδ+–Nδ− moiety.

scholarly journals Ultrafast formation of domain walls of a charge density wave in SmTe3

2021 ◽  
Vol 103 (5) ◽  
Author(s):  
M. Trigo ◽  
P. Giraldo-Gallo ◽  
J. N. Clark ◽  
M. E. Kozina ◽  
T. Henighan ◽  
...  
Keyword(s):  
Charge Density ◽  
Charge Density Wave ◽  
Domain Walls ◽  
Density Wave ◽  
A Charge

Ultrafast switching to an insulating-like metastable state by amplitudon excitation of a charge density wave

2021 ◽  
Author(s):  
Naotaka Yoshikawa ◽  
Hiroki Suganuma ◽  
Hideki Matsuoka ◽  
Yuki Tanaka ◽  
Pierre Hemme ◽  
...  
Keyword(s):  
Charge Density ◽  
Metastable State ◽  
Charge Density Wave ◽  
Density Wave ◽  
Ultrafast Switching ◽  
A Charge

scholarly journals Ultrafast spot-profile LEED of a charge-density wave phase transition

2021 ◽  
Vol 118 (22) ◽  
pp. 221603
Author(s):  
G. Storeck ◽  
K. Rossnagel ◽  
C. Ropers
Keyword(s):  
Phase Transition ◽  
Charge Density ◽  
Charge Density Wave ◽  
Density Wave ◽  
Wave Phase ◽  
Charge Density Wave Phase ◽  
A Charge

Grid Lifetime Measurements and Shell Model Calculations In 59Ni

1991 ◽  
Author(s):  
S. Ulbig ◽  
K. P. Lieb ◽  
H. G. Börner ◽  
S. J. Robinson ◽  
J. G. L. Booten
Keyword(s):  
Shell Model ◽  
Lifetime Measurements ◽  
Model Calculations

Low-lying Negative-parity Levels of 17N and 18N

1984 ◽  
Vol 37 (1) ◽  
pp. 17 ◽  
Author(s):  
FC Barker
Keyword(s):  
Shell Model ◽  
Weak Coupling ◽  
Coupling Model ◽  
Negative Parity ◽  
Positive Parity ◽  
Model Calculations

On the basis of a weak-coupling model, adjustments are made to the interactions used in the full shell model calculations of Millener in order to fit the experimental energies of the low-lying negativeparity levels of 16N and of the low-lying positive-parity levels of 180 and 190 . The predicted energies of the low-lying negative-parity levels of 17N then agree better with experiment, while those for 18N lead to suggested spin assignments for the observed levels.

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