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Alicia Torre  One of the best experts on this subject based on the ideXlab platform.

A study of the relationships between Unpaired Electron density, spindensity and cumulant matrices
Theoretical Chemistry Accounts, 2011CoAuthors: Luis Lain, Alicia Torre, Diego R. Alcoba, Roberto C BochicchioAbstract:This work describes the derivation of simple relationships between the density matrix of effectively Unpaired Electrons and the spindensity matrix in N Electron systems. The link between both devices turns out to be the oneElectron matrix arising from the diagonal contraction of the cumulant matrix corresponding to the secondorder reduced density matrix. We study some features of this contracted matrix, showing its usefulness to describe the Electronic correlation. Numerical determinations performed in selected systems with different spin symmetries confirm the theoretical predictions.

laplacian field of the effectively Unpaired Electron density determination of many body effects on Electron distributions
Journal of Physical Chemistry A, 2007CoAuthors: Rosana M Lobayan, Roberto C Bochicchio, Luis Lain, Alicia TorreAbstract:This work carries out the study of the Laplacian field function of the Electron density L(r) = nabla2rho(r) splitted in two contributions rho(r) = rho(p)(r) + rho(u)(r), which correspond to the effectively paired and effectively Unpaired Electron densities, respectively. The visualization of the concentration and depletion of these fields and their spatial localization show no contribution of the effectively Unpaired Electrons to the conventional bonding among two centers, but the field nabla2rho(u)(r) provides an interesting structure. We also study the reliability of the information contained in the partitioning of this Electron density field function for describing nonclassical bondings as the threecenter twoElectron ones.

on the definition of the effectively Unpaired Electron density matrix a similarity measure approach
Chemical Physics Letters, 2006CoAuthors: Diego Ricardo Alcoba, Roberto C Bochicchio, Luis Lain, Alicia TorreAbstract:The mathematical concepts of similarity and distance in metric spaces are used to relate Takatsuka et al. and HeadGordon definitions of the effectively Unpaired Electron density matrix. This approach opens the possibility of new suitable definitions of this quantity to given purposes.

Electron density topology in molecular systems paired and Unpaired densities
Journal of Chemical Physics, 2005CoAuthors: Rosana M Lobayan, Roberto C Bochicchio, Luis Lain, Alicia TorreAbstract:This work studies the partitioning of the Electron density into two contributions which are interpreted as the paired and the effectively Unpaired Electron densities. The topological features of each density field as well as of the total density are described localizing the corresponding critical points in simple selected molecules (local formalism). The results show that Unpaired Electrondensity concentrations occur out of the topological bonding regions whereas the paired Electron densities present accumulations inside those regions. A comparison of these results with those arising from population analysis techniques (nonlocal or integrated formalisms) is reported.

bond orders and their relationships with cumulant and Unpaired Electron densities
Journal of Physical Chemistry A, 2003CoAuthors: Alicia Torre, Luis Lain, Roberto C BochicchioAbstract:This paper reports the relationships among different covalent bondorder concepts, secondorder cumulant densities, and atomic populations of effectively Unpaired Electrons. This framework leads to the derivation of suitable formulas to perform population analyses at correlated level in Mulliken and topological versions. Numerical determinations in some molecules confirm the usefulness of these proposals for describing chemical bondings.
Roberto C Bochicchio  One of the best experts on this subject based on the ideXlab platform.

A study of the relationships between Unpaired Electron density, spindensity and cumulant matrices
Theoretical Chemistry Accounts, 2011CoAuthors: Luis Lain, Alicia Torre, Diego R. Alcoba, Roberto C BochicchioAbstract:This work describes the derivation of simple relationships between the density matrix of effectively Unpaired Electrons and the spindensity matrix in N Electron systems. The link between both devices turns out to be the oneElectron matrix arising from the diagonal contraction of the cumulant matrix corresponding to the secondorder reduced density matrix. We study some features of this contracted matrix, showing its usefulness to describe the Electronic correlation. Numerical determinations performed in selected systems with different spin symmetries confirm the theoretical predictions.

laplacian field of the effectively Unpaired Electron density determination of many body effects on Electron distributions
Journal of Physical Chemistry A, 2007CoAuthors: Rosana M Lobayan, Roberto C Bochicchio, Luis Lain, Alicia TorreAbstract:This work carries out the study of the Laplacian field function of the Electron density L(r) = nabla2rho(r) splitted in two contributions rho(r) = rho(p)(r) + rho(u)(r), which correspond to the effectively paired and effectively Unpaired Electron densities, respectively. The visualization of the concentration and depletion of these fields and their spatial localization show no contribution of the effectively Unpaired Electrons to the conventional bonding among two centers, but the field nabla2rho(u)(r) provides an interesting structure. We also study the reliability of the information contained in the partitioning of this Electron density field function for describing nonclassical bondings as the threecenter twoElectron ones.

on the definition of the effectively Unpaired Electron density matrix a similarity measure approach
Chemical Physics Letters, 2006CoAuthors: Diego Ricardo Alcoba, Roberto C Bochicchio, Luis Lain, Alicia TorreAbstract:The mathematical concepts of similarity and distance in metric spaces are used to relate Takatsuka et al. and HeadGordon definitions of the effectively Unpaired Electron density matrix. This approach opens the possibility of new suitable definitions of this quantity to given purposes.

Electron density topology in molecular systems paired and Unpaired densities
Journal of Chemical Physics, 2005CoAuthors: Rosana M Lobayan, Roberto C Bochicchio, Luis Lain, Alicia TorreAbstract:This work studies the partitioning of the Electron density into two contributions which are interpreted as the paired and the effectively Unpaired Electron densities. The topological features of each density field as well as of the total density are described localizing the corresponding critical points in simple selected molecules (local formalism). The results show that Unpaired Electrondensity concentrations occur out of the topological bonding regions whereas the paired Electron densities present accumulations inside those regions. A comparison of these results with those arising from population analysis techniques (nonlocal or integrated formalisms) is reported.

bond orders and their relationships with cumulant and Unpaired Electron densities
Journal of Physical Chemistry A, 2003CoAuthors: Alicia Torre, Luis Lain, Roberto C BochicchioAbstract:This paper reports the relationships among different covalent bondorder concepts, secondorder cumulant densities, and atomic populations of effectively Unpaired Electrons. This framework leads to the derivation of suitable formulas to perform population analyses at correlated level in Mulliken and topological versions. Numerical determinations in some molecules confirm the usefulness of these proposals for describing chemical bondings.
David R Tyler  One of the best experts on this subject based on the ideXlab platform.

density functional studies of 19 Electron organometallic complexes investigation of possible ligand distortions and calculation of the epr parameters and Unpaired Electron distributions in cpcr co 2no cpw no 2p ome 3 cpmo co3 p ome 3 and co co 3 2 3 bis diphenylphosphino maleic anhydride
Organometallics, 2000CoAuthors: Dale Braden A And, David R TylerAbstract:Density functional theory (DFT) was used to calculate the equilibrium geometries and EPR hyperfine coupling constants for the CpCr(CO)2NO and CpW(NO)2P(OMe)3 19Electron complexes. The calculated EPR hyperfine parameters for both molecules were found to be in good agreement with the experimental values. The EPR study on CpCr(CO)2NO indicated that the nitrosyl ligand bends significantly when the neutral 18Electron parent molecule is reduced. This was confirmed by the DFT calculations, although the degree of bending is not as large as that predicted from the EPR analysis. The calculated geometry for CpW(NO)2P(OMe)3 showed that the nitrosyl ligands are not significantly bent, which is consistent with the crystal structure of the related compound CpW(NO)2P(OPh)3. In both CpCr(CO)2NO and CpW(NO)2P(OMe)3, the Unpaired Electron is localized to about the same extent on the NO ligands. It is concluded that, although distortion of a ligand implies significant localization of the Unpaired Electron on that ligand...

density functional theory calculations on 19 Electron organometallic complexes the mn co 5cl anion the difference between Unpaired Electron density and spin density due to spin polarization
Organometallics, 1998CoAuthors: Dale Braden A And, David R TylerAbstract:The anisotropic hyperfine coupling (hfc) constants for the 19Electron Mn(CO)5Cl complex, 1, and for the 17Electron Mn(CO)4Cl complex, 2, were calculated using density functional theory (DFT). The calculated hfc values for 1 are in good agreement with the experimental ones reported in two EPR studies, which were not able to distinguish between 1 and 2. The Mn−CO(axial) bond dissociation energy in 1 was calculated to be 19 kcal/mol, which shows that 1 is stable to loss of axial CO. These data indicate that the species observed in the EPR experiments was the 19Electron complex, 1. The Unpaired Electron population of the manganese dz2 orbital indicated by the SOMO of the DFT wave function (ca. 0.2−0.3) is significantly less than that obtained from the two EPR analyses (0.49, 0.63), which neglected spin polarization. The calculations show that spin polarization in 1 causes the spin density (as measured by EPR) to differ significantly from the Unpaired Electron density (SOMO). It is concluded that neglect ...

solvent effects on Electron delocalization in paramagnetic organometallic complexes solvent manipulation of the amount of 19 Electron character in co co 3l2 l2 a chelating phosphine
Journal of the American Chemical Society, 1992CoAuthors: Fei Mao, David R Tyler, Mitchell R M Bruce, Alice E Bruce, Anne L Rieger, Philip H RiegerAbstract:Infared, ERS, and Electronic absorption spectroscopic studies are reported on the 18+δ Ci(CO) 3 L 2 complex. (L 2 is the chelating phosphine ligand 2,3bis(diphenylphosphino)malec anhydride. 18+δ complexes are 19Electron complexes in which the Unpaired Electron is primarily localized on a ligand.) The spectra are solvent dependent and are interpreted in terms of increased delocalization of the Unpaired Electron form an L 2 (π * ) orbital onto the Co(CO) 3 portion of the molecule with decreasing solvent polarity
Luis Lain  One of the best experts on this subject based on the ideXlab platform.

A study of the relationships between Unpaired Electron density, spindensity and cumulant matrices
Theoretical Chemistry Accounts, 2011CoAuthors: Luis Lain, Alicia Torre, Diego R. Alcoba, Roberto C BochicchioAbstract:This work describes the derivation of simple relationships between the density matrix of effectively Unpaired Electrons and the spindensity matrix in N Electron systems. The link between both devices turns out to be the oneElectron matrix arising from the diagonal contraction of the cumulant matrix corresponding to the secondorder reduced density matrix. We study some features of this contracted matrix, showing its usefulness to describe the Electronic correlation. Numerical determinations performed in selected systems with different spin symmetries confirm the theoretical predictions.

laplacian field of the effectively Unpaired Electron density determination of many body effects on Electron distributions
Journal of Physical Chemistry A, 2007CoAuthors: Rosana M Lobayan, Roberto C Bochicchio, Luis Lain, Alicia TorreAbstract:This work carries out the study of the Laplacian field function of the Electron density L(r) = nabla2rho(r) splitted in two contributions rho(r) = rho(p)(r) + rho(u)(r), which correspond to the effectively paired and effectively Unpaired Electron densities, respectively. The visualization of the concentration and depletion of these fields and their spatial localization show no contribution of the effectively Unpaired Electrons to the conventional bonding among two centers, but the field nabla2rho(u)(r) provides an interesting structure. We also study the reliability of the information contained in the partitioning of this Electron density field function for describing nonclassical bondings as the threecenter twoElectron ones.

on the definition of the effectively Unpaired Electron density matrix a similarity measure approach
Chemical Physics Letters, 2006CoAuthors: Diego Ricardo Alcoba, Roberto C Bochicchio, Luis Lain, Alicia TorreAbstract:The mathematical concepts of similarity and distance in metric spaces are used to relate Takatsuka et al. and HeadGordon definitions of the effectively Unpaired Electron density matrix. This approach opens the possibility of new suitable definitions of this quantity to given purposes.

Electron density topology in molecular systems paired and Unpaired densities
Journal of Chemical Physics, 2005CoAuthors: Rosana M Lobayan, Roberto C Bochicchio, Luis Lain, Alicia TorreAbstract:This work studies the partitioning of the Electron density into two contributions which are interpreted as the paired and the effectively Unpaired Electron densities. The topological features of each density field as well as of the total density are described localizing the corresponding critical points in simple selected molecules (local formalism). The results show that Unpaired Electrondensity concentrations occur out of the topological bonding regions whereas the paired Electron densities present accumulations inside those regions. A comparison of these results with those arising from population analysis techniques (nonlocal or integrated formalisms) is reported.

bond orders and their relationships with cumulant and Unpaired Electron densities
Journal of Physical Chemistry A, 2003CoAuthors: Alicia Torre, Luis Lain, Roberto C BochicchioAbstract:This paper reports the relationships among different covalent bondorder concepts, secondorder cumulant densities, and atomic populations of effectively Unpaired Electrons. This framework leads to the derivation of suitable formulas to perform population analyses at correlated level in Mulliken and topological versions. Numerical determinations in some molecules confirm the usefulness of these proposals for describing chemical bondings.
A I Mikhailov  One of the best experts on this subject based on the ideXlab platform.

Unpaired Electron localization and delocalization in macromolecules with a system of conjugated c c bonds
High Energy Chemistry, 2014CoAuthors: D A Gordon, V A Volodina, A I MikhailovAbstract:The radical polymerization of acetylene monomers has been studied in a wide temperature range (77–340 K) using EPR spectroscopy, calorimetry, chromatography, and gravimetry It has been found that the growing macroradical is active, and its Unpaired Electron is localized at a terminal fragment of the molecule. However, it lost its activity even at small chain lengths (less than ten monomer units) because of delocalization of the Unpaired Electron along the system of conjugated double bonds.

low temperature polymerization in p diethynylbenzene crystal localization of Unpaired Electron in poly conjugated system
Journal of Low Temperature Physics, 2005CoAuthors: D A Gordon, A I MikhailovAbstract:Optical and ESR spectroscopy study has revealed that the stereoregular polymer is formed under UV or γirradiation of paradiethynylbenzene (DEB) crystals over a wide temperature range (77–300 K). It has been shown that the Unpaired Electron of the macroradical of the propagating linear polymer chain (77–230 K) is localized on the terminal monomer link to give a doublet splitting in the ESR spectrum. Delocalization of Unpaired Electron in the polyconjugated system takes place at 230–300 K by addition of the linear macroradical to the double bond of the polymer. In this case, a normal polyenetype radical, observed during the polymerization of acetylenic monomers at elevated temperatures, is formed and shows singlet splitting with the width of ΔH = 1 mT in the ESR spectrum. The encounter of the macroradical with the double bond probably occurs via polymer chain propagation.

on the localization of the Unpaired Electron in a macroradical of a propagating polymer chain during low temperature solid phase polymerization of p diethynylbenzene
Journal of Photochemistry and Photobiology Achemistry, 1995CoAuthors: D A Gordon, A I MikhailovAbstract:Abstract An Electron spin resonance (ESR) study of the UV or γinduced polymerization of pdiethynylbenzene (DEB) crystals over a wide temperature range (77–300 K) has revealed that the Unpaired Electron of the macroradical of the propagating polymer chain (77–230 K) is localized on the terminal monomer link to give a doublet splitting in the ESR spectrum. Delocalization in the polyconjugated system takes place at 230–310 K by addition of the linear macroradical to the double bond of the polymer. In this case, a normal polyenetype radical, observed during the polymerization of acetylenic monomers at elevated temperatures, is formed and shows a singlet splitting with a width of ΔH ∼ 1 mT in the ESR spectrum. The encounter of the macroradical with the double bond probably occurs via polymer chain propagation.

the growth and interaction of conjugated polymer chains the Unpaired Electron localization
Journal of Polymer Science Part B, 1994CoAuthors: D A Gordon, A I MikhailovAbstract:An ESR method was used to study the structure of the macroradical of the propagating chain Rp in the lowtemperature, solidphase polymerization of pdiethynylbenzene (DEB). The ESR spectra for γirradiated DEB samples and those of DEB deuterated in the ethynyl group showed that in the range 77–230 K, the Unpaired Electron of the macroradical was localized on one of the monomer links. At 230–310 K, its delocalization in a polyconjugated system took place because of addition of a linear macroradical to a double bond of a polymer molecule. The encounter of the macroradical with double bond probably occurs as polymer chain propagation. © 1994 John Wiley & Sons, Inc.