We present a self-interaction-corrected (SIC) density-functional-theory (DFT) approach for the description of systems with an unpaired electron or hole such as spin-$1∕2$ defect centers in solids or radicals. Our functional is easy to implement and its minimization does not require additional computational effort with respect to ordinary DFT functionals. In particular it does not present multiminima, as do the conventional SIC functionals. We successfully validate the method studying the hole self-trapping in quartz associated with the Al substitutional impurity. We show that our approach corrects for the well-known failures of standard DFT functionals in this system.

• Received 1 March 2005

DOI:https://doi.org/10.1103/PhysRevB.71.205210