Surface Cluster Models for V2O5 - Studies of the Importance of Local Geometry

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Title:Surface Cluster Models for V2O5 - Studies of the Importance of Local Geometry
Creators:
Witko, Małgorzata
Tokarz, Renata
Hermann, Klaus
Journal or Publication Title:
Collection of Czechoslovak Chemical Communications, 63, 9, pp. 1355-1367
Uncontrolled Keywords:Cluster model calculations, ZINDO, Semiempirical calculations, V<sub>2</sub>O<sub>5</sub>, Local geometries, Vanadium oxide

Abstract

Catalytic properties of the vanadium pentoxide (010) surface are discussed based upon semiempirical quantum chemical calculations using cluster models. Special attention is paid to the role of the second layer in discussing the geometrical factor by using the semiempirical ZINDO approach. Local electronic properties near the different surface oxygen sites are analyzed with the help of Mulliken populations and Meyer bond order indices. Different optimization procedures (with various boundary conditions) are performed for diverse V-O clusters modeling one and two layers. Electronic parameters of the clusters are found to be similar for the cluster in the bulk and optimized geometry. The optimized geometry of the cluster remains much closer to the surface geometry when the optimization is done for the whole cluster, excluding the saturated hydrogen atoms. Optimization of the small fragment of the cluster, results in the significant rearrangement of the cluster structure and leads to the "warped" geometry (bridging oxygen as well as vanadium atoms are shifted out of the surface). Two types of boundary conditions assumed during the optimization process lead to similar results, the optimization of all atoms in the cluster (with saturating hydrogen atoms kept frozen) and the same optimization in the presence of the second layer. The presence of the second layer stabilizes the surface geometry. The role of the second layer is also shown in a formation of an oxygen vacancy at the bridging position.

Title:Surface Cluster Models for V2O5 - Studies of the Importance of Local Geometry
Creators:
Witko, Małgorzata
Tokarz, Renata
Hermann, Klaus
Uncontrolled Keywords:Cluster model calculations, ZINDO, Semiempirical calculations, V<sub>2</sub>O<sub>5</sub>, Local geometries, Vanadium oxide
Divisions:Life and Chemical Sciences > Institute of Organic Chemistry and Biochemistry > Collection of Czechoslovak Chemical Communications
Journal or Publication Title:Collection of Czechoslovak Chemical Communications
Volume:63
Number:9
Page Range:pp. 1355-1367
ISSN:0010-0765
E-ISSN:1212-6950
Publisher:Institute of Organic Chemistry and Biochemistry
Related URLs:
URLURL Type
http://dx.doi.org/10.1135/cccc19981355UNSPECIFIED
ID Code:1386
Item Type:Article
Deposited On:06 Feb 2009 17:09
Last Modified:06 Feb 2009 16:09

Citation

Witko, Małgorzata; Tokarz, Renata; Hermann, Klaus (1998) Surface Cluster Models for V2O5 - Studies of the Importance of Local Geometry. Collection of Czechoslovak Chemical Communications, 63 (9). pp. 1355-1367. ISSN 0010-0765

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