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

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 Li2Mg2 and further corroborate it with an application to the experimentally well studied CO/Cu(111) system. Our results are in good agreement with near-full configuration interaction (CI) calculations in the former case and experimental adsorbate binding energies in the latter. (C) 1998 Published by Elsevier Science B.V. All rights reserved.