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arXiv · 0912.3197

Calculation of model Hamiltonian parameters for LaMnO_3 using maximally localized Wannier functions

Roman Kovacik·Claude Ederer
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Abstract

Maximally localized Wannier functions (MLWFs) based on Kohn-Sham band-structures provide a systematic way to construct realistic, materials specific tight-binding models for further theoretical analysis. Here, we construct MLWFs for the Mn e_g bands in LaMnO_3, and we monitor changes in the MLWF matrix elements induced by different magnetic configurations and structural distortions. From this we obtain values for the local Jahn-Teller and Hund's rule coupling strength, the hopping amplitudes between all nearest and further neighbors, and the corresponding reduction due to the GdFeO_3-type distortion. By comparing our results with commonly used model Hamiltonians for manganites, where electrons can hop between two "e_g-like" orbitals located on each Mn site, we find that the most crucial limitation of such models stems from neglecting changes in the underlying Mn(d)-O(p) hybridization.

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Roman Kovacik, Claude Ederer. 2009-12-16. Calculation of model Hamiltonian parameters for LaMnO_3 using maximally localized Wannier functions. https://doi.org/10.1103/physrevb.81.245108

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