Good performance of the M06 family of hybrid meta generalized gradient approximation density functionals on a difficult case: CO adsorption on MgO(001)

Rosendo Valero; José R B Gomes; Donald G Truhlar; Francesc Illas

doi:10.1063/1.2982923

Good performance of the M06 family of hybrid meta generalized gradient approximation density functionals on a difficult case: CO adsorption on MgO(001)

J Chem Phys. 2008 Sep 28;129(12):124710. doi: 10.1063/1.2982923.

Authors

Rosendo Valero¹, José R B Gomes, Donald G Truhlar, Francesc Illas

Affiliation

¹ Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, USA.

PMID: 19045051
DOI: 10.1063/1.2982923

Abstract

The adsorption of CO on Mg(001) constitutes a challenge for current density functional approximations because of its weak interaction character. In the present work we show that the M06-2X and M06-HF exchange-correlation functionals are the first ones to provide a simultaneously satisfactory description of adsorbate geometry, vibrational frequency shift, and adsorption energy of CO on MgO(001). For a sufficiently large embedded cluster model, the three functionals of the M06 family-which contain a nonzero percentage of Hartree-Fock exchange (M06, M06-2X, and M06-HF)-all predict positive C-O vibrational shifts, in agreement with the experimental findings, while the local M06-L functional gives large negative shifts. Moreover, the shifts computed with the M06-2X and M06-HF potentials are in good agreement with the experimental shift of +14 cm(-1). The interaction energy (D(e)) calculated with M06-2X and M06-HF is approximately 6.0 kcal/mol, which agrees well with the D(e) value ( approximately 4 kcal/mol) deduced from the D(0) obtained in thermal desorption measurements on single-crystal surfaces.