The effect of double counting, spin density, and Hund interaction in the different DFT plus U functionals

A systematic comparative study has been performed to better understand DFT+U (density functional theory +/- U) method. We examine the effect of choosing different double counting and exchange-correlation functionals. The calculated energy distribution and the Hund-J dependence of potential profile for representative configurations clearly show the different behaviors of each DFT +/- U formalism. In particular, adopting spin-dependent exchange-correlation functionals likely leads to undesirable magnetic solution. Our analyses are further highlighted by real material examples ranging from insulating oxides (MnO and NiO) to metallic magnetic systems (SrRuO3 and BaFe2As2). The current work sheds new light on understanding DFT+U and provides a guideline to use the related methods.