Adsorption of successive layers of H2 molecules on a model copper surface: performances of second to fifth rung exchange-correlation functionals

G. Cilpa (1) , J. Colin (2) , F. Labat (2) , C. Adamo (2) , Gilberte Chambaud (1)

1 MSME - Laboratoire de Modélisation et Simulation Multi Echelle
2 LECIME - Laboratoire d'Electrochimie, Chimie des Interfaces et Modélisation pour l'Energie (LECIME - UMR 7575)

The interaction of H2 molecules with a Cu(100) metallic surface has been investigated by DFT approaches using a (H2)nCu13 cluster model. Nine exchange-correlation functionals, belonging to the Generalized Gradient Approximations (GGA), meta GGA (mGGA), hybrid Kohn-Sham/Hartree- Fock models, either based on GGAs or mGGAs, range-separated hybrids, and double-hybrid families, have been tested on the chemisorption and physisorption processes involving one or two H2 layers. The addition of an empirical correction for dispersion has also been tested for some of these functionals. The calculated energies and structural parameters were compared to sophisticated Multi Reference Con guration Interaction including Davidson's correction for quadruple excitations (MRCI+Q). Our results show that among the nine considered exchange-correlation functionals, none can accurately reproduce all processes involved in the successive layers adsorption. Although an hybrid based on a mGGA such as M06-2X can quantitatively describe both the physisorption step and dissociation barriers involved in the adsorption of the rst H2, it fails to reproduce its chemisorption. On the other hand, signi cant discrepancies with the reference post-HF data are obtained for the description of the second layer interaction, no matter which functional is considered, outlining the need of improvement and/or development of exchange-correlation functionals suitable for complex systems such as H2/H2Cu.

Mots clés: DFT Physisorption H2 Copper Cluster

Domaines: Chimie théorique et/ou physique

G. Cilpa, J. Colin, F. Labat, C. Adamo, Gilberte Chambaud. Adsorption of successive layers of H2 molecules on a model copper surface: performances of second to fifth rung exchange-correlation functionals. Theoretical Chemistry Accounts: Theory, Computation, and Modeling, 2012, 131 (3), pp.1189. ⟨10.1007/s00214-012-1189-8⟩. ⟨hal-00789708⟩