Orbital mixing in CO chemisorption on transition metal surfaces

✍ Scribed by P. Hu; D.A. King; M.-H. Lee; M.C. Payne

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 391 KB
• Volume: 246
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(95)01070-p

✦ Synopsis

The chemisorption of CO on metal surfaces is widely accepted as a model for understanding chemical bonding between molecules and solid surfaces, but is nevertheless still a controversial subject. Ab initio total energy calculations using density functional theory with gradient corrections for CO chemisorption on an extended Pd{110} slab yield good agreement with experimental adsorption energies. Examination of the spatial distribution of individual Bloch states demonstrates that the conventional model for CO chemisorption involving charge donation from CO 5(r states to metal states and back-donation from metal states into CO 21r states is too simplistic, but the computational results provide direct insight into the chemical bonding within the framework of orbital mixing (or hybridisation). The results provide a sound basis for understanding the bonding between molecules and metal surfaces. How a molecule bonds to an extended metal surface is a fundamental issue. Chemical bonding in individual molecules and in extended systems such as metals are well understood and documented. However, many aspects of bonding between a molecule and an extended metal surface remain unclear. The chemisorption of CO has been extensively used, both experimentally and theoretically, as a prototype for such studies (see, for example, Ref.

[1]). CO is itself, of course, an important molecule in many catalytic reactions on metal surfaces. Despite this, it is still a subject of controversy [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Using the Hiickel molecular orbital approach, Blyholder [2] proposed that a or-bond is formed between the CO carbon atom and a metal atom, and that further