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Calculation of the 4,5‐dihydro‐1,3,2‐dithiazolyl radical g tensor components by the coupled‐perturbed Kohn–Sham hybrid density functional and configuration interaction methods: a comparative study
Author(s) -
Mattar Saba M.,
Durelle Jeremy
Publication year - 2010
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2649
Subject(s) - chemistry , tensor (intrinsic definition) , atomic orbital , electron paramagnetic resonance , density functional theory , multireference configuration interaction , complete active space , computational chemistry , electron , atomic physics , nuclear magnetic resonance , quantum mechanics , physics , mathematics , geometry , basis set
The g tensor components of the 4,5‐dihydro‐1,3,2‐dithiazolyl (H2DTA•) radical, which is a basic building block for molecular magnets and spintronic devices, is calculated by the coupled‐perturbed Kohn–Sham (CPKS) hybrid density functional (HDF) and multireference configuration interaction‐sum over states (MRCI‐SOS) techniques. In both methods, the diagonalized g tensor principal axes are found to be aligned with the radical's inertial axes. The tensor components are in very good agreement with those determined experimentally by electron paramagnetic resonance (EPR) spectroscopy. The MRCI technique produced g tensor components that are more accurate than those obtained by the CPKS‐HDF method. Nonetheless, to get reasonable MRCI results, one must include the in‐plane and out‐of‐plane interactions in an unbiased way. The minimum reference space that satisfies these conditions is generated from a complete active space of nine electrons in six orbitals [CAS(9,6)] and contains a 1 , a 2 , b 1 and b 2 type orbitals. In addition, the number of roots in the MRCI‐SOS g tensor expansion should include all excited states that range from 0 to 56 000 cm −1 . The most accurate results are obtained using an MRCI‐SOS/CAS(13,9) calculation. These g tensor components are within the experimental accuracy range of 1000 ppm. The one‐ and two‐electron contributions to the g tensor components are separated and individually analyzed. The very good agreement with experiment opens the door for further accurate calculations of spin Hamiltonian tensors of larger DTA• radicals. Copyright © 2010 John Wiley & Sons, Ltd.