Solution of Poisson's equation for finite systems using plane-wave methods

Reciprocal-space methods for solving Poisson's equation for finite charge distributions are investigated. Improvements to previous proposals are presented, and their performance is compared in the context of a real-space density-functional-theory code. Two basic methodologies are followed: calculation of correction terms and imposition of a cutoff to the Coulomb potential. We conclude that these methods can be safely applied to finite or aperiodic systems with a reasonable control of speed and accuracy. PACS Nos.: 2.30.Jr, 71.15.–m