Kavli Affiliate: Kristin A. Persson
| First 5 Authors: Guy C. Moore, Matthew K. Horton, Alexander M. Ganose, Martin Siron, Kristin A. Persson
| Summary:
Hubbard U and Hund J values provide a measure of the self-interaction between
correlated electrons, and are crucial parameters in the formalism of density
functional theory with a "plus U" correction, known as DFT+U and DFT+U+J. The
linear response (LR) methodology has proven to be a computationally effective
and self-contained method for computing accurate U and J values. This study
provides a high-throughput computational analysis of the U and J values applied
to transition metal d-electron states in a representative set of magnetic
transition metal oxides (TMOs). In a less conventional pursuit, over two
hundred system-specific U and J corrections are calculated for oxygen 2p
on-site occupations. The distributions of values are analyzed for structures
containing manganese, iron and nickel-containing compounds, with sample sizes
of over 150 for each species. In addition, periodic tables of U and J values
are presented for transition metal and oxygen species from a combined data set
of over 800 TMO compounds. Our work provides a frame of reference for
researchers who utilize DFT+U to study TMO materials, and to gain insight into
the distribution of U values that may be relevant to their applications. An
atomate workflow is presented for calculating U and J values automatically on
massively parallel supercomputing architectures. To validate this method, the
spin-canting magnetic structure and unit cell parameters of a known
multiferroic, olivine LiNiPO4, are predicted using the computed Hubbard U and
Hund J values for Ni-d and O-p on-site occupancies, and are compared with
experiment. It was confirmed that in addition to Ni-d U values, applying a
separate Hund J to Ni-d has a strong effect on Ni-moment canting angle.
Additionally, including a O-p U value results in a significantly improved
agreement between DFT-computed lattice parameters and experiment.
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