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The importance of anisotropic Coulomb interaction in LaMnO3

Mellan, T. A., Cora, F., Grau-Crespo, R. and Ismail-Beigi, S. (2015) The importance of anisotropic Coulomb interaction in LaMnO3. Physical Review B, 92 (8). 085151. ISSN 1098-0121

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To link to this item DOI: 10.1103/PhysRevB.92.085151

Abstract/Summary

In low-temperature anti-ferromagnetic LaMnO3, strong and localized electronic interactions among Mn 3d electrons prevent a satisfactory description from standard local density and generalized gradient approximations in density functional theory calculations. Here we show that the strong on-site electronic interactions are described well only by using direct and exchange corrections to the intra-orbital Coulomb potential. Only DFT+U calculations with explicit exchange corrections produce a balanced picture of electronic, magnetic and structural observables in agreement with experiment. To understand the reason, a rewriting of the functional form of the +U corrections is presented that leads to a more physical and transparent understanding of the effect of these correction terms. The approach highlights the importance of Hund’s coupling (intra-orbital exchange) in providing anisotropy across the occupation and energy eigenvalues of the Mn d states. This intra-orbital exchange is the key to fully activating the Jahn-Teller distortion, reproducing the experimental band gap and stabilizing the correct magnetic ground state in LaMnO3. The best parameter values for LaMnO3 within the DFT(PBEsol)+U framework are determined to be U = 8 eV and J = 1.9 eV.

Item Type:Article
Refereed:Yes
Divisions:Faculty of Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
ID Code:41319
Uncontrolled Keywords:LaMnO3, density functional theory, Hubbard correction
Publisher:American Physical Society

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