resumo
A series of reactions including water, oxygen, hydrogen and nitric oxide dissociation and carbon monoxide or nitric oxide oxidations catalyzed by metallic surfaces have been investigated by means of periodic density functional calculations with the main aim of establishing the importance of spin polarization when the substrate is nonmagnetic. Numerical differences in the calculated total energies and bond lengths of the breaking/forming bonds corresponding to spin restricted or spin unrestricted formalisms are usually smaller than the inherent error of density functional theory based methods. Nevertheless, it is important to insist on the fact that the spin polarized solution exists and is lower in energy than the one corresponding to the spin restricted formalism, as one would expect, and from a practical point of view, results obtained without taking spin polarization into account lead to the same description of the potential energy surface.
palavras-chave
DENSITY-FUNCTIONAL THEORY; 1ST-ROW DIATOMIC-MOLECULES; TOTAL-ENERGY CALCULATIONS; AUGMENTED-WAVE METHOD; DIELS-ALDER REACTION; GAS SHIFT REACTION; NI-DOPED MGO; RELATIVE ENERGIES; AU(321) SURFACE; BASIS-SET
categoria
Chemistry; Physics
autores
Fajin, JLC; Cordeiro, MNDS; Gomes, JRB; Illas, F
nossos autores
agradecimentos
The authors wish to thank Prof. Konstantin Neyman for a stimulating discussion which triggered the present work. We acknowledge financial support from Portuguese Fundacao para a Ciencia e Tecnologia (FCT) and its Programme Ciencia 2007; FEDER for financial support to REQUIMTE (grant no. PEst-C/EQB/LA0006/2011 from FCT) and to CICECO (grant no. PEst-C/CTM/LA0011/2011 from FCT); the Spanish MICINN (grants FIS2008-02238, CTQ2007-30547-E/BQU, CTQ2009-07647/BQU) and Generalitat de Catalunya (grants 2009SGR1041 and XRQTC). J.L.C.F. acknowledges FCT for the grant SFRH/BPD/64566/2009 cofinanced by the Fundo Social Europeu (FSE) and F.I. acknowledges additional support through the ICREA Academia award for excellence in research.