Potential energy hypersurface for ammonia adsorbing onto nickel oxide

Autor: Stephen R. Cain, Luis J. Matienzo, F. Emmi
Rok vydání: 1990
Předmět:
Zdroj: The Journal of Physical Chemistry. 94:4985-4990
ISSN: 1541-5740
0022-3654
DOI: 10.1021/j100375a042
Popis: The approach of an ammonia molecule to the surface of nickel oxide was probed theoretically by performing band calculations at the extended Hueckel level on model systems. A hump in the energy vs Ni-NH{sub 3} separation curve was attributed to the initial repulsion of the NH{sub 3} lone-pair electrons by the electron-rich 3d orbitals of nickel. However, once the 3d{sub z}2 orbital was pushed above the Fermi level, the antibonding component of the Ni 3d{sub z}2-NH{sub 3} lone-pair interaction was depopulated and the Ni-NH{sub 3} interaction became strongly attractive. This was demonstrated to be completely analogous to the intended crossing of occupied and unoccupied orbitals in rearrangements of small molecules. A limited study of the potential energy surface was performed, the results of which suggested that NH{sub 3} prefers to attack directly at a surface Ni atom. From the principles derived in the NiO-NH{sub 3} study, qualitative predictions concerning the dynamics of NH{sub 3} adsorbing onto Cr{sub 2}O{sub 3} and Cu{sub 2}O were made.
Databáze: OpenAIRE