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Use of charge sensitivity analysis in diagnosing chemisorption clusters: Minimum‐energy coordinate and Fukui function study of model toluene–[V 2 O 5 ] systems
Author(s) -
Nalewajski Roman F.,
Michalak Artur
Publication year - 1995
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560560516
Subject(s) - chemistry , chemisorption , charge (physics) , atomic physics , population , partial charge , cluster (spacecraft) , atom (system on chip) , computational chemistry , molecular physics , molecule , physics , quantum mechanics , demography , adsorption , sociology , computer science , programming language , organic chemistry , embedded system
Charge sensitivity analysis ( CSA ) is carried out for model toluene–vanadium pentoxide chemisorption complexes involving the two‐pyramidal model of the active site on the (010)—V 2 O 5 surface. Maps of the electrostatic potential around the adsorbate and the substrate cluster are used to rationalize energetical preferences of alternative perpendicular and parallel arrangements of the toluene ring relative to the pyramid bases, known from previous SCF MO studies. The minimum‐energy coordinates ( MEC ) in the electron population space are determined from the CSA semiempirical, finite difference atomic hardness matrix for the actual SCF MO charges in the chemisorption clusters. They represent collective charge displacements which minimize the system energy per unit change in the oxidation state of a specified atom, thus providing a convenient diagnostic tool for testing the alternative charge rearrangements and range of perturbations due to the chemisorption bond or changes in the cluster environment. The MEC relaxed hardnesses diagnose mode stabilities and together with the MEC topologies identify the most probable locations of the adsorbate activation. Finally, the atomic Fukui function indices are used to explore trends in the distribution of the external charge transfer due to the system environment. © 1995 John Wiley & Sons, Inc.