Structural stability, chemical order and reactivity pattern of MopWq clusters, with p + q = 8

REINALDO PIS DIEZ; FAUSTINO AGUILERA GRANJA

EUROPEAN PHYSICAL JOURNAL D

SPRINGER

Lugar: Berlin; Año: 2013 vol. 67 p. 251 - 262

1434-6060

The electronic structure and related properties of free-standing Mop Wq atomic clusters, withp+q = 8, are investigated within the framework of the fully unconstrained version of the density functionaltheory as implemented in the SIESTA code. Starting from the structures of the lowest-energy isomers ofpure Mo8 and W8 , they are decorated for any possible homotops and their geometries are re-optimized.Binding energies, excess energies and second differences in binding energies are reported and used to dis-cuss relative stabilities of different isomers. Interatomic distances, magnetic moments, average coordinationnumbers and order parameters are also reported to achieve a better understanding of the structural evolu-tion of the species when Mo atoms are replaced by W atoms and vice versa. Adiabatic ionization potentials,adiabatic electronic affinities and absolute hardnesses are also shown and discussed in the context of thepotential reactivity of Mop Wq clusters against hydrotreatment processes. Those reactivity indexes suggestthat the Mo3 W5 aggregate should be a good candidate to take part in a reaction governed by a chargetransfer process.