We report linear-response kinetic-energy density functionals, which show significant improvement over the Wang-Teter, Perrot, Smargiassi-Madden, Wang-Govind-Carter functionals, yet still maintain O(N ln N) scaling. Numerical tests show that these functionals, which contain a double-density-dependent kernel, can reproduce the Kohn-Sham results almost exactly for several aluminum bulk phases. We further show that with a sensible choice of the uniform background density, energies of formation for the low-index aluminum surfaces, where the density variations are very large, can be reproduced to within reasonable accuracy. ͓S0163-1829͑99͒01848-2͔ I. BACKGROUND

A first-principles embedding theory that combines the salient features of density functional theory ͑DFT͒ and traditional quantum chemical methods is presented. The method involves constructing a DFT-based embedding potential and then using it as a one-electron operator within a very accurate ab initio calculation. We demonstrate how DFT calculations can be systematically improved via this procedure. The scheme is tested using two closed shell systems, a toy model Li 2 Mg 2 , and the experimentally well characterized CO/Cu͑111͒ system. Our results are in good agreement with near full configuration interaction calculations in the former case and experimental adsorbate binding energies in the latter. This method provides the means to systematically include electron correlation in a local region of a condensed phase.

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We present an improvement over the Wang-Teter, Perrot, and Smargiassi-Madden kinetic-energy functionals without going beyond linear-response theory and without introducing a density-dependent kernel. The improved functionals were tested on bulk aluminum, and excellent results were obtained. Accurate densityfunctional calculations using the new functionals on systems larger than one can study by traditional Kohn-Sham methods are demonstrated. ͓S0163-1829͑98͒00244-6͔

We extend our recently reported embedding theory [J. Chem. Phys. 110, 7677 (1999)] to calculate not only improved descriptions of ground states, but now also localized excited states in a periodically infinite condensed phase. A local region of the solid is represented by a small cluster for which high quality quantum chemical calculations are performed. The interaction of the cluster with the extended condensed phase is taken into account by an effective embedding potential. This potential is calculated by periodic density functional theory (DFT) and is used as a one-electron operator in subsequent cluster calculations. Among a variety of benchmark calculations, we investigate a CO molecule adsorbed on a Pd(111) surface. By performing complete active space self-consistent field, configuration interaction (CI), and Møller–Plesset perturbation theory of order n (MP-n), we not only were able to obtain accurate adsorption energies via local corrections to DFT, but also vertical excitation energies for an internal (52*) excitation within the adsorbed CO molecule. We demonstrate that our new scheme is an efficient and accurate approach for the calculation of local excited states in bulk metals and on metal surfaces. Additionally, a systematic means of improving locally on ground state properties is provided