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Magnetic exchange in {Gd-III-radical} complexes: method assessment, mechanism of coupling and magneto-structural correlations

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Title Magnetic exchange in {Gd-III-radical} complexes: method assessment, mechanism of coupling and magneto-structural correlations
 
Creator GUPTA, T
RAJESHKUMAR, T
RAJARAMAN, G
 
Subject SINGLE-MOLECULE MAGNETS
GENERALIZED GRADIENT APPROXIMATION
NITRONYL NITROXIDE RADICALS
TRANSITION-METAL-COMPLEXES
HYBRID DENSITY FUNCTIONALS
RARE-EARTH COMPLEXES
SPIN GROUND-STATE
CORRELATION-ENERGY
GADOLINIUM(III) COMPLEXES
LANTHANIDE COMPLEXES
 
Description Density functional studies have been performed on ten different {Gd-III-radical} complexes exhibiting both ferro and antiferromagnetic exchange interaction with an aim to assess a suitable exchange-correlation functional within DFT formalism. This study has also been extended to probe the mechanism of magnetic coupling and to develop suitable magneto-structural correlations for this pair. Our method assessments reveal the following order of increasing accuracy for the evaluation of J values compared to experimental coupling constants: B(40HF)LYP < BHandHLYP < TPSSH < PW91 < PBE < BP86 < OLYP < BLYP < PBE0 < X3LYP < B3LYP < B2PLYP. Grimme's double-hybrid functional is found to be superior compared to other functionals tested and this is followed very closely by the conventional hybrid B3LYP functional. At the basis set front, our calculations reveal that the incorporation of relativistic effect is important in these calculations and the relativistically corrected effective core potential (ECP) basis set is found to yield better Js compared to other methods. The supposedly empty 5d/6s/6p orbitals of Gd-III are found to play an important role in the mechanism of magnetic coupling and different contributions to the exchange terms are probed using Molecular Orbital (MO) and Natural Bond Orbital (NBO) analysis. Magneto-structural correlations for Gd-O distances, Gd-O-N angles and Gd-O-N-C dihedral angles are developed where the bond angles as well as dihedral angle parameters are found to dictate the sign and strength of the magnetic coupling in this series.
 
Publisher ROYAL SOC CHEMISTRY
 
Date 2014-12-28T12:01:32Z
2014-12-28T12:01:32Z
2014
 
Type Article
 
Identifier PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 16(28)14568-14577
1463-9076
1463-9084
http://dx.doi.org/10.1039/c4cp00214h
http://dspace.library.iitb.ac.in/jspui/handle/100/16425
 
Language English