Spin Polarization versus Spin Delocalization. Topological Electron and Spin Density Analysis of the Rotational Automerization of Allyl Radical Including Electron Correlation Effects1

1994 ◽  
Vol 98 (44) ◽  
pp. 11379-11393 ◽  
Author(s):  
Rainer Glaser ◽  
Godwin Sik-Cheung Choy
Keyword(s):  
Spin Density ◽  
Spin Polarization ◽  
Electron Correlation ◽  
Allyl Radical ◽  
Density Analysis ◽  
Spin Delocalization

scholarly journals Insights on spin delocalization and spin polarization mechanisms in crystals of azido copper(II) dinuclear complexes through the electron spin density Source Function

2017 ◽  
Vol 73 (4) ◽  
pp. 565-583 ◽  
Author(s):  
Carlo Gatti ◽  
Giovanni Macetti ◽  
Leonardo Lo Presti
Keyword(s):  
Spin Density ◽  
Spin Polarization ◽  
Source Function ◽  
Reference Points ◽  
Dinuclear Complexes ◽  
Azido Group ◽  
Local Spin ◽  
Whole Space ◽  
Spin Delocalization ◽  
Spin Densities

The Source Function (SF) tool was applied to the analysis of thetheoreticalspin density in azido CuIIdinuclear complexes, where the azido group, acting as a coupler between the CuIIcations, is linked to the metal centres either in an end-on or in an end–end fashion. Results for only the former structural arrangement are reported in the present paper. The SF highlights to which extent the magnetic centres contribute to determine the local spin delocalization and polarization at any point in the dimetallic complex and whether an atom or group of atoms of the ligands act in favour or against a given local spin delocalization/polarization. Ball-and-stick atomic SF percentage representations allow for a visualization of the magnetic pathways and of the specific role played by each atom along these paths, at given reference points. Decomposition of SF contributions in terms of a magnetic and of a relaxation component provides further insight. Reconstruction of partial spin densities by means of the Source Function has for the first time been introduced. At variance with the standard SF percentage representations, such reconstructions offer a simultaneous view of the sources originating from specific subsets of contributing atoms, in a selected molecular plane or in the whole space, and are therefore particularly informative. The SF tool is also used to evaluate the accuracy of the analysed spin densities. It is found that those obtained at the unrestricted B3LYP DFT level, relative to those computed at the CASSCF(6,6) level, greatly overestimate spin delocalization to the ligands, but comparatively underestimate magnetic connection (spin transmission) among atoms, along the magnetic pathways. As a consequence of its excessive spin delocalization, the UB3LYP method also overestimates spin polarization mechanisms between the paramagnetic centres and the ligands. Spin delocalization measures derived from the refinement of Polarized Neutron Diffraction data seem in general superior to those obtained through the DFT UB3LYP approach and closer to the far more accurate CASSCF results. It is also shown that a visual agreement on the spin-resolved electron densities ραand ρβderived from different approaches does not warrant a corresponding agreement between their associated spin densities.

Salts of Ferricinium Cation and its Homologues: NMR Investigation, II EPR and NMR Spectra of sym-Polymethyl Substituted Ferricinium Cations

1980 ◽  
Vol 35 (11) ◽  
pp. 1415-1419 ◽  
Author(s):  
R. B. Materikova ◽  
V. N. Babin ◽  
S. P. Solodovnikov ◽  
I. R. Lyatifov ◽  
P. V. Petrovsky ◽  
...  
Keyword(s):  
Density Distribution ◽  
Spin Density ◽  
Spin Polarization ◽  
Nmr Spectra ◽  
General Pattern ◽  
Spin Density Distribution ◽  
Determining Factors ◽  
Spin Delocalization ◽  
C Nmr

Abstract The EPR, 1H and 13C NMR spectra of methylferricinium hexafluorophosphates, [(MenCp)2Fe]PF6, n = 0-5, have been recorded. HFS constants have been estimated for all the ligand atoms. The general pattern of the spin density distribution is shown to depend on the superposition of the various mechanisms of spin delocalization. For the majority of the cations the determining factors has been found to be represented by spin polarization over the π-skeleton.

Electronic structure study of new family of high-Tc Fe-superconductors based on BaFe2As2 in presence of dopants Rh and Pd.

MRS Advances ◽  
2019 ◽  
Vol 4 (61-62) ◽  
pp. 3365-3372
Author(s):  
Ronald Columbié-Leyva ◽  
Jacques Soullard ◽  
Ilya G. Kaplan
Keyword(s):  
Spin Density ◽  
Electron Correlation ◽  
Population Analysis ◽  
Ferromagnetic State ◽  
Structure Study ◽  
Cluster Method ◽  
High Tc ◽  
New Family ◽  
Correlation Level ◽  
Density Transfer

AbstractThe superconductivity has a long history. One of the most recent discoveries is the superconductivity in the Fe- based family with anti- ferromagnetic state at ambient temperature. In this type of material, the transition to the superconductivity state was found in presence of different dopants. In this report we present the results of calculations of the cluster representing Ba4Fe5As8 in presence of Rh and Pd as dopants. The methodology of Embedded Cluster Method at the MP2 electron correlation level was employed. The population analysis showed two main features: the independence of charge density transfer from the spin density transfer and, the presence of orbitals with electron density but without spin density. The observed properties correspond to the RVB mechanism for the superconductivity transition proposed by Anderson for cuprates. This confirms our conclusions obtained in the same material doped by Co and Ni.

ESR Studies on 205Tl Hyperfine Couplings in the Radical Cations of Tl(III)Porphyrins

1974 ◽  
Vol 29 (12) ◽  
pp. 1827-1833 ◽  
Author(s):  
Chr. Mengersen ◽  
J. Subramanian ◽  
J.-H. Fuhrhop ◽  
K. M. Smith
Keyword(s):  
Spin Density ◽  
Spin Polarization ◽  
Radical Cations ◽  
Esr Spectra ◽  
Cation Radicals ◽  
Bilinear Relation ◽  
Tetraphenyl Porphyrin ◽  
Pi Orbitals ◽  
Spin Densities ◽  
Hyperfine Couplings

The isotropic 205Tl hyperfine couplings obtained from the ESR spectra of the radical cations of Tl (III) meso tetraphenyl porphyrin (TPP), octaethyl porphyrin (OEP) and octaethyl chlorin (OEC) are reported. The radical cations were generated by electrooxidation in dichloromethane as solvent. A Karplus-Fraenkel type bilinear relation is used to interpret the 205Tl couplings, taking into account the sigma-pi spin polarization of Tl -N bonds by the spin density at the nitrogen atoms in the ligand as well as the direct pi interaction of the orbitals of Tl with the pi orbitals of the ligand. It is shown that for the cation radicals of Tl porphyrins, both these mechanisms contribute to the Tl couplings whereas for the cation radicals of Co- and Zn-porphyrins the sigma-pi polarization alone is sufficient to account for the metal hyperfine couplings. It is suggested that Tl-hyperfine couplings can be used to estimate the nitrogen spin densities of porphyrin radical systems when the nitrogen splittings are not resolved in the ESR spectra.

scholarly journals Electron correlation and two dimensionality in the spin-density-wave phase of(TMTTF)2Brunder pressure

2003 ◽  
Vol 67 (21) ◽  
Author(s):  
A. Ishikawa ◽  
N. Matsunaga ◽  
K. Nomura ◽  
T. Sasaki ◽  
T. Nakamura ◽  
...  
Keyword(s):  
Spin Density ◽  
Electron Correlation ◽  
Density Wave ◽  
Spin Density Wave ◽  
Wave Phase

Tuning of Spin Density Wave Strengths in Quasi-One-Dimensional Mixed-Halogen-Bridged Nickel(III) Complexes with Strong Electron Correlation, [NiIII(chxn)2Cl1-xBrx](NO3)2

2002 ◽  
Vol 41 (20) ◽  
pp. 4993-4995 ◽  
Author(s):  
Toshio Manabe ◽  
Kohei Yokoyama ◽  
Sachie Furukawa ◽  
Chihiro Kachi-Terajima ◽  
Kazuya Nakata ◽  
...  
Keyword(s):  
Spin Density ◽  
Electron Correlation ◽  
Density Wave ◽  
Spin Density Wave ◽  
Strong Electron Correlation ◽  
Strong Electron ◽  
One Dimensional
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