Linear-scaling DFT +  U with full local orbital optimization

• Published in: Physical review. B, Condensed matter and materials physics Vol. 85; no. 8
• Main Authors: O’Regan, David D., Hine, Nicholas D. M., Payne, Mike C., Mostofi, Arash A.
• Format: Journal Article
• Language: English
• Published: 13-02-2012
• Subjects: Condensed matter; Convergence; Density functional theory; Mathematical analysis; Mathematical models; Nickel; Optimization; Orbitals
• ISSN: 1098-0121; 1550-235X
• DOI: 10.1103/PhysRevB.85.085107

We present an approach to the DFT + U method (density functional theory + Hubbard model) within which the computational effort for calculation of ground-state energies and forces scales linearly with system size. We employ a formulation of the Hubbard model using nonorthogonal projector functions to define the localized subspaces, and we apply it to a local orbital DFT method including in situ orbital optimization. The resulting approach thus combines linear-scaling and systematic variational convergence. We demonstrate the scaling of the method by applying it to nickel-oxide nanoclusters with sizes exceeding 7000 atoms.