Title

Weak antiferromagnetic coupling in molecular ring is predicted correctly by density functional theory plus Hubbard U

Authors

Authors

S. Gangopadhyay; A. E. Masunov; E. Poalelungi;M. N. Leuenberger

Comments

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Abbreviated Journal Title

J. Chem. Phys.

Keywords

TRANSITION-METAL DIMERS; MAGNETIC-PROPERTIES; ELECTRONIC-STRUCTURE; MANGANESE COMPLEX; SPIN; EXCHANGE; WHEEL; DFT; MN-12; STATE; Physics, Atomic, Molecular & Chemical

Abstract

We apply density functional theory with empirical Hubbard U parameter (DFT+U) to study Mn-based molecular magnets. Unlike most previous DFT+U studies, we calibrate U parameters for both metal and ligand atoms using five binuclear manganese complexes as the benchmarks. We note delocalization of the spin density onto acetate ligands due to pi-back bonding, inverting spin polarization of the acetate oxygen atoms relative to that predicted from superexchange mechanism. This inversion may affect the performance of the models that assume strict localization of the spins on magnetic centers for the complexes with bridging acetate ligands. Next, we apply DFT+U methodology to Mn-12 molecular wheel and find antiparallel spin alignment for the weakly interacting fragments Mn-6, in agreement with experimental observations. Using the optimized geometry of the ground spin state instead of less accurate experimental geometry was found to be crucial for this good agreement. The protocol tested in this study can be applied for the rational design of single molecule magnets for molecular spintronics and quantum computing applications. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3421645]

Journal Title

Journal of Chemical Physics

Volume

132

Issue/Number

24

Publication Date

1-1-2010

Document Type

Article

Language

English

First Page

7

WOS Identifier

WOS:000279740200009

ISSN

0021-9606

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