Accurate ab initio energetics of extended systems via explicit correlation embedded in a density functional environment

Ž . We present a new embedding technique that combines density functional theory DFT and explicit electron-correlation techniques. We construct a periodic-DFT-based embedding potential as a local one-electron operator within more accurate electron-correlation calculations. We demonstrate how DFT calculations can be systematically improved via this procedure. We benchmark the method against nearly exact calculations with a simple model of Li Mg and further corroborate it with 2 2 Ž . an application to the experimentally well studied COrCu 111 system. Our results are in good agreement with near-full Ž . configuration interaction CI calculations in the former case and experimental adsorbate binding energies in the latter. q 1998 Published by Elsevier Science B.V. All rights reserved.