Theoretical study of chemi- and physisorption processes of H2 molecules on a (100) surface of silver

SURFACE SCIENCE

卷:602

Article

Cilpa, G.¹  Guitou, M.¹  Chambaud, G.¹ 

[1] Univ Paris Est, Lab Modelisat & Simulat Multi Echelle, CNRS, MSME,FRE 3160, F-77454 Marne La Vallee, France

关键词: physisorption of H-2;    silver surface;    cluster model;    multi-layer process;    ab initio methods;    electronic structure;   

DOI  :  10.1016/j.susc.2008.07.025

来源: Elsevier

【 摘 要 】

A model system consisting of a cluster of 13 Ag atoms and n (n = 1,2,3) H-2 molecules has been used to study, by ab initio methods, the structural and energetic characteristics of the chemi- and physisorption processes of H-2 on a (100) surface of silver. The dissociative chemisorption of a first H-2 molecule is analyzed in terms of hydrides formation and it is shown that several electronic states are interacting in the vicinity of the activation barrier leading to complex electronic processes. The energy of the physisorption interaction of the first H-2 molecule for different orientations and that of further H-2 molecules coming directly on top of the first chemisorbed one are determined with highly correlated wavefunctions. As for the (H-2)(n)CU13 system, already studied with similar approaches, it is found for the (H-2)(n)Ag-13 system that the physisorption energy of the second layer is enhanced by a factor close to two compared to that of the first layer due to dipolar interactions with the polarized surface. The physisorption energy of the third and further layers tends to the van der Waals H-2/H-2 interaction energy. (C) 2008 Elsevier B.V. All rights reserved.

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