scholarly journals Auxiliary Atomic Relay Center Facilitates Enhanced Magnetic Couplings in Blatter’s Radical

2021 ◽  
Author(s):  
Ashima Bajaj ◽  
Rishu Khurana ◽  
Md. Ehesan Ali
Keyword(s):  
Density Functional ◽  
Exchange Interactions ◽  
Nitronyl Nitroxide ◽  
Functional Theory ◽  
Spin Interactions ◽  
Ferromagnetic Exchange ◽  
Self Consistent Field ◽  
Molecular Rigidity ◽  
Ferromagnetic Interactions ◽  
Torsional Angles

<div>The recent accomplishments in obtaining the strong ferromagnetic exchange interactions in organic diradicals have made the field quite fascinating and even more promising towards its technological applications. In this context, herein we report a unique combination of remarkably strong ferromagnetic exchange interactions coupled with the molecular rigidity utilizing super-stable Blatter’s radical as a spin source. The planar analogues of the parent Blatter’s radical obtained by annulation with a chalcogen coupled to nitronyl nitroxide (NN) are investigated using density functional theory (DFT) along with the wave function based multi-configurational self-consistent field (MCSCF) methods e.g. CASSCF/NEVPT2. The calculations reveal phenomenal modulation in exchange couplings upon annulation such that remarkably strong ferromagnetic interactions are realized especially for a certain class of the Blatter - nitronyl nitroxide diradicals. The modulation of spin spin interactions is rationalised by variation in spin density distribution and molecular torsional angles. We demonstrate that annulation in OMMs opens an additional coupling pathway via auxiliary X-atom acting as atomic relay center which strongly manipulates the magnitude of exchange couplings.</div>

scholarly journals Auxiliary Atomic Relay Center Facilitates Enhanced Magnetic Couplings in Blatter’s Radical

2021 ◽  
Author(s):  
Ashima Bajaj ◽  
Rishu Khurana ◽  
Md. Ehesan Ali
Keyword(s):  
Density Functional ◽  
Exchange Interactions ◽  
Nitronyl Nitroxide ◽  
Functional Theory ◽  
Spin Interactions ◽  
Ferromagnetic Exchange ◽  
Self Consistent Field ◽  
Molecular Rigidity ◽  
Ferromagnetic Interactions ◽  
Torsional Angles

<div>The recent accomplishments in obtaining the strong ferromagnetic exchange interactions in organic diradicals have made the field quite fascinating and even more promising towards its technological applications. In this context, herein we report a unique combination of remarkably strong ferromagnetic exchange interactions coupled with the molecular rigidity utilizing super-stable Blatter’s radical as a spin source. The planar analogues of the parent Blatter’s radical obtained by annulation with a chalcogen coupled to nitronyl nitroxide (NN) are investigated using density functional theory (DFT) along with the wave function based multi-configurational self-consistent field (MCSCF) methods e.g. CASSCF/NEVPT2. The calculations reveal phenomenal modulation in exchange couplings upon annulation such that remarkably strong ferromagnetic interactions are realized especially for a certain class of the Blatter - nitronyl nitroxide diradicals. The modulation of spin spin interactions is rationalised by variation in spin density distribution and molecular torsional angles. We demonstrate that annulation in OMMs opens an additional coupling pathway via auxiliary X-atom acting as atomic relay center which strongly manipulates the magnitude of exchange couplings.</div>

First-Principles Study on Co-Doped ZnO with Oxygen Vacancy

2010 ◽  
Vol 154-155 ◽  
pp. 124-129
Author(s):  
Zhen Zhen Weng ◽  
Zhi Gao Huang ◽  
Wen Xiong Lin
Keyword(s):  
Oxygen Vacancy ◽  
First Principles ◽  
Density Functional ◽  
Exchange Interactions ◽  
First Principles Calculations ◽  
Functional Theory ◽  
Ferromagnetic Exchange ◽  
Ferromagnetic Ground State ◽  
Doped Zno ◽  
Co Doped

The interatomic exchange interactions and the electronic structure of Co-doped ZnO with and without oxygen vacancy have been investigated by the first-principles calculations based on density functional theory. It is found that the oxygen vacancy can strengthen the ferromagnetic exchange interaction between Co atoms and might be available for carrier mediation. The oxygen vacancy near to the Co atoms is more favorable for the ferromagnetic ground state.

scholarly journals Quasi-1D XY antiferromagnet Sr2Ni(SeO3)2Cl2 at Sakai-Takahashi phase diagram

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
E. S. Kozlyakova ◽  
A. V. Moskin ◽  
P. S. Berdonosov ◽  
V. V. Gapontsev ◽  
S. V. Streltsov ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Long Range ◽  
Density Functional ◽  
Uniaxial Anisotropy ◽  
Exchange Interactions ◽  
Spin Liquid ◽  
Functional Theory ◽  
One Dimensional ◽  
Ordered Phases ◽  
Experimental Findings

AbstractUniform quasi-one-dimensional integer spin compounds are of interest as a potential realization of the Haldane conjecture of a gapped spin liquid. This phase, however, has to compete with magnetic anisotropy and long-range ordered phases, the implementation of which depends on the ratio of interchain J′ and intrachain J exchange interactions and both uniaxial D and rhombic E single-ion anisotropies. Strontium nickel selenite chloride, Sr2Ni(SeO3)2Cl2, is a spin-1 chain system which passes through a correlations regime at Tmax ~ 12 K to long-range order at TN = 6 K. Under external magnetic field it experiences the sequence of spin-flop at Bc1 = 9.0 T and spin-flip transitions Bc2 = 23.7 T prior to full saturation at Bsat = 31.0 T. Density functional theory provides values of the main exchange interactions and uniaxial anisotropy which corroborate the experimental findings. The values of J′/J = 0.083 and D/J = 0.357 place this compound into a hitherto unoccupied sector of the Sakai-Takahashi phase diagram.

Theoretical Methods

1992 ◽  
Author(s):  
John A. Tossell ◽  
David J. Vaughan
Keyword(s):  
Density Functional Theory ◽  
Quantum Chemistry ◽  
Density Functional ◽  
Point Group ◽  
Theoretical Background ◽  
Wave Functions ◽  
General Reference ◽  
Functional Theory ◽  
Hartree Fock ◽  
Self Consistent Field

In this chapter, the most important quantum-mechanical methods that can be applied to geological materials are described briefly. The approach used follows that of modern quantum-chemistry textbooks rather than being a historical account of the development of quantum theory and the derivation of the Schrödinger equation from the classical wave equation. The latter approach may serve as a better introduction to the field for those readers with a more limited theoretical background and has recently been well presented in a chapter by McMillan and Hess (1988), which such readers are advised to study initially. Computational aspects of quantum chemistry are also well treated by Hinchliffe (1988). In the section that follows this introduction, the fundamentals of the quantum mechanics of molecules are presented first; that is, the “localized” side of Fig. 1.1 is examined, basing the discussion on that of Levine (1983), a standard quantum-chemistry text. Details of the calculation of molecular wave functions using the standard Hartree-Fock methods are then discussed, drawing upon Schaefer (1972), Szabo and Ostlund (1989), and Hehre et al. (1986), particularly in the discussion of the agreement between calculated versus experimental properties as a function of the size of the expansion basis set. Improvements on the Hartree-Fock wave function using configuration-interaction (CI) or many-body perturbation theory (MBPT), evaluation of properties from Hartree-Fock wave functions, and approximate Hartree-Fock methods are then discussed. The focus then shifts to the “delocalized” side of Fig. 1.1, first discussing Hartree-Fock band-structure studies, that is, calculations in which the full translational symmetry of a solid is exploited rather than the point-group symmetry of a molecule. A good general reference for such studies is Ashcroft and Mermin (1976). Density-functional theory is then discussed, based on a review by von Barth (1986), and including both the multiple-scattering self-consistent-field Xα method (MS-SCF-Xα) and more accurate basis-function-density-functional approaches. We then describe the success of these methods in calculations on molecules and molecular clusters. Advances in density-functional band theory are then considered, with a presentation based on Srivastava and Weaire (1987). A discussion of the purely theoretical modified electron-gas ionic models is followed by discussion of empirical simulation, and we conclude by mentioning a recent approach incorporating density-functional theory and molecular dynamics (Car and Parrinello, 1985).

scholarly journals Redox-Active Dysprosium Single-Molecule Magnet: Spectro-Electrochemistry and Theoretical Investigations

2019 ◽  
Vol 5 (3) ◽  
pp. 46 ◽  
Author(s):  
Guglielmo Fernandez Garcia ◽  
Vincent Montigaud ◽  
Lucie Norel ◽  
Olivier Cador ◽  
Boris Le Guennic ◽  
...  
Keyword(s):  
Single Molecule ◽  
Density Functional ◽  
Functional Theory ◽  
Single Molecule Magnet ◽  
Complete Active Space ◽  
Consistent Field ◽  
Redox Active ◽  
Theoretical Investigations ◽  
Td Dft ◽  
Self Consistent Field

The mononuclear single-molecule magnet (SMM) [Dy(tta)3(L)]⋅C6H14 (1) (where tta− = 2-thenoyltrifluoroacetonate and L = 4,5-bis(propylthio)-tetrathiafulvalene-2-(2-pyridyl)benzimidazole-methyl-2-pyridine) was studied by spectro-electrochemistry. The resulting electronic spectra of the three oxidation states 1, 1+∙, and 12+ were rationalized by time-dependent density functional theory (TD-DFT) calculations starting from the DFT optimized structures. The modulation of the magnetic anisotropy of the DyIII center upon oxidation was also inspected at the Complete Active Space Self-Consistent Field (CASSCF) level of calculation.

Theoretical study of NO3− interacting with carbon nanotube

Open Physics ◽  
2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Silvete Guerini ◽  
David Azevedo ◽  
Maria Lima ◽  
Ivana Zanella ◽  
Josué Filho
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Quantum Mechanical ◽  
Mechanical Interaction ◽  
Electronic Density ◽  
Functional Theory ◽  
Consistent Field ◽  
The Density Functional Theory ◽  
Self Consistent Field ◽  
Field Form

AbstractThis paper deals with quantum mechanical interaction of no 3− with (5,5) and (8,0) swcnts. To perform this we have made an ab initio calculation based on the density functional theory. In these framework the electronic density plays a central role and it was obtained of a self-consistent field form. It was observed through binding energy that NO3− molecule interacts with each nanotube in a physisorption regime. We propose these swcnts as a potential filter device due to reasonable interaction with NO3− molecule. Besides this type of filter could be reusable, therefore after the filtering, the swcnts could be separated from NO3− molecule.

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