COLL 13 |
| Hybrid functionals, containing a fraction of the non local Fock exchange, find wide spread use in Quantum Chemistry. The most successful functionals are the B3LYP functional and the recently suggested HSE03 functional, which is based on Perdews gradient corrected functional and therefore fulfills the homogeneous electron gas limit. Here calculations for extended systems, comprising semiconductors, insulators and metals are presented. These show that the B3LYP functional results in large errors for the atomization energies of metals and semiconductors, whereas the HSE03 functional works reasonably well for all considered test systems. Lattice constants are also predicted very accurately by the HSE03 functional but are too large using the B3LYP functional. We show this to be related to the LYP correlation energy, which fails to attain the free electron gas limit. Furthermore, we show that results for CO adsorption on transition metal surfaces (Cu, Ru-Ag, Os-Pt) are not satisfactory for any of the present density functionals. The HSE03 functional, clearly overestimates the adsorption energy and gives the wrong site order on Pt(111). B3LYP results are in reasonable agreement with experiment, but given the larger failure for atomization energies of metals, we argue this agreement to be mostly fortuitous. |
|
Electronic Structure Modeling of Heterogeneous Catalysis
9:00 AM-12:00 PM, Sunday, August 19, 2007 BCEC -- 152, Oral
Division of Colloid & Surface Chemistry |