posted on 2023-12-05, 16:07authored byThéophile Tchakoua, Tim Jansen, Youri van Nies, Rebecca F. A. van den Elshout, Bart A. B. van Boxmeer, Saskia P. Poort, Michelle G. Ackermans, Gabriel Spiller Beltrão, Stefan A. Hildebrand, Steijn E. J. Beekman, Thijs van der Drift, Sam Kaart, Anthonie Šantić, Esmee E. Spuijbroek, Nick Gerrits, Mark F. Somers, Geert-Jan Kroes
The production of
a majority of chemicals involves heterogeneous
catalysis at some stage, and the rates of many heterogeneously catalyzed
processes are governed by transition states for dissociative chemisorption
on metals. Accurate values of barrier heights for dissociative chemisorption
on metals are therefore important to benchmarking electronic structure
theory in general and density functionals in particular. Such accurate
barriers can be obtained using the semiempirical specific reaction
parameter (SRP) approach to density functional theory. However, this
approach has thus far been rather ad hoc in its choice of the generic
expression of the SRP functional to be used, and there is a need for
better heuristic approaches to determining the mixing parameters contained
in such expressions. Here we address these two issues. We investigate
the ability of several mixed, parametrized density functional expressions
combining exchange at the generalized gradient approximation (GGA)
level with either GGA or nonlocal correlation to reproduce barrier
heights for dissociative chemisorption on metal surfaces. For this,
seven expressions of such mixed density functionals are tested on
a database consisting of results for 16 systems taken from a recently
published slightly larger database called SBH17. Three expressions
are derived that exhibit high tunability and use correlation functionals
that are either of the PBE GGA form or of one of two limiting nonlocal
forms also describing the attractive van der Waals interaction in
an approximate way. We also find that, for mixed density functionals
incorporating GGA correlation, the optimum fraction of repulsive RPBE
GGA exchange obtained with a specific GGA density functional is correlated
with the charge-transfer parameter, which is equal to the difference
in the work function of the metal surface and the electron affinity
of the molecule. However, the correlation is generally not large and
not large enough to obtain accurate guesses of the mixing parameter
for the systems considered, suggesting that it does not give rise
to a very effective search strategy.