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Download file# Density Functional Theory for Molecule–Metal Surface Reactions: When Does the Generalized Gradient Approximation Get It Right, and What to Do If It Does Not

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posted on 2020-12-09, 16:05 authored by Nick Gerrits, Egidius W. F. Smeets, Stefan Vuckovic, Andrew D. Powell, Katharina Doblhoff-Dier, Geert-Jan KroesWhile
density functional theory (DFT) is perhaps the most used
electronic structure theory in chemistry, many of its practical aspects
remain poorly understood. For instance, DFT at the generalized gradient
approximation (GGA) tends to fail miserably at describing gas-phase
reaction barriers, while it performs surprisingly well for many molecule–metal
surface reactions. GGA-DFT also fails for many systems in the latter
category, and up to now it has not been clear when one may expect
it to work. We show that GGA-DFT tends to work if the difference between
the work function of the metal and the molecule’s electron
affinity is greater than ∼7 eV and to fail if this difference
is smaller, with sticking of O

_{2}on Al(111) being a spectacular example. Using dynamics calculations we show that, for this system, the DFT problem may be solved as done for gas-phase reactions, i.e., by resorting to hybrid functionals, but using screening at long-range to obtain a correct description of the metal. Our results suggest the GGA error in the O_{2}+ Al(111) barrier height to be functional driven. Our results also suggest the possibility to compute potential energy surfaces for the difficult-to-treat systems with computationally cheap nonself-consistent calculations in which a hybrid functional is applied to a GGA density.