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arXiv · 1104.1292

Effect of Hubbard U on the construction of low energy Hamiltonians for LaMnO_3 via maximally localized Wannier functions

Roman Kovacik·Claude Ederer
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Abstract

We use maximally localized Wannier functions to construct tight-binding (TB) parameterizations for the e_g bands of LaMnO_3 based on first principles electronic structure calculations. We compare two different ways to represent the relevant bands around the Fermi level: i) a d-p model that includes atomic-like orbitals corresponding to both Mn(d) and O(p) states in the TB basis, and ii) an effective e_g model that includes only two e_g-like Wannier functions per Mn site. We first establish the effect of the Jahn-Teller distortion within the d-p model, and then compare the TB representations for both models obtained from GGA+U calculations with different values of the Hubbard parameter U. We find that in the case of the d-p model the TB parameters are rather independent on the specific value of U, if compared with the mean-field approximation of an appropriate multi-band Hubbard Hamiltonian. In contrast, the U dependence of the TB parameters for the effective e_g model cannot easily be related to a corresponding mean-field Hubbard model, and therefore these parameters depend critically on the specific value of U, and more generally on the specific exchange-correlation functional, used in the electronic structure calculation.

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Roman Kovacik, Claude Ederer. 2011-04-07. Effect of Hubbard U on the construction of low energy Hamiltonians for LaMnO_3 via maximally localized Wannier functions. https://doi.org/10.1103/physrevb.84.075118

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