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How to find an optimum cluster size through topological site properties: MoS x model clusters
Author(s) -
Silva Alexander M.,
Borges Itamar
Publication year - 2011
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.21802
Subject(s) - cluster (spacecraft) , density functional theory , charge density , multipole expansion , quadrupole , dipole , chemistry , partition (number theory) , magnetic monopole , charge (physics) , catalysis , topology (electrical circuits) , chemical physics , computational chemistry , molecular physics , atomic physics , physics , computer science , quantum mechanics , mathematics , organic chemistry , biochemistry , combinatorics , programming language
Computational investigations in catalysis frequently use model clusters to represent realistically the catalyst and its reaction sites. Detailed knowledge of the molecular charge, thus electronic density, of a cluster would then allow physical and chemical insights of properties and can provide a procedure to establish their optimum size for catalyst studies. For this purpose, an approach is suggested to study model clusters based on the distributed multipole analysis (DMA) of molecular charge properties. After full density functional theory (DFT) geometry optimization of each cluster, DMA computed from the converged DFT one‐electron density matrix allowed the partition of the corresponding cluster charge distribution into monopole, dipole, and quadrupole moments on the atomic sites. The procedure was applied to MoS 2 model clusters Mo 10 S 18 , Mo 12 S 26 , Mo 16 S 32 , Mo 23 S 48 , and Mo 27 S 54 . This analysis provided detailed features of the charge distribution of each cluster, focused on the 10 1 0 (Mo or metallic edge) and 1 010 (sulfur edge) active planes. Properties of the Mo 27 S 54 cluster, including the formation of HDS active surfaces, were extensively discussed. The effect of cluster size on the site charge distribution properties of both planes was evaluated. The results showed that the Mo 16 S 32 cluster can adequately model both active planes of real size Mo 27 S 54 . These results can guide future computational studies of MoS 2 catalytic processes. Furthermore, this approach is of general applicability. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011