The adsorption energy
of a molecule onto the surface
of a material
underpins a wide array of applications, spanning heterogeneous catalysis,
gas storage, and many more. It is the key quantity where experimental
measurements and theoretical calculations meet, with agreement being
necessary for reliable predictions of chemical reaction rates and
mechanisms. The prototypical molecule–surface system is CO
adsorbed on MgO, but despite intense scrutiny from theory and experiment,
there is still no consensus on its adsorption energy. In particular,
the large cost of accurate many-body methods makes reaching converged
theoretical estimates difficult, generating a wide range of values.
In this work, we address this challenge, leveraging the latest advances
in diffusion Monte Carlo (DMC) and coupled cluster with single, double,
and perturbative triple excitations [CCSD(T)] to obtain accurate predictions
for CO on MgO. These reliable theoretical estimates allow us to evaluate
the inconsistencies in published temperature-programed desorption
experiments, revealing that they arise from variations in employed
pre-exponential factors. Utilizing this insight, we derive new experimental
estimates of the (electronic) adsorption energy with a (more) precise
pre-exponential factor. As a culmination of all of this effort, we
are able to reach a consensus between multiple theoretical calculations
and multiple experiments for the first time. In addition, we show
that our recently developed cluster-based CCSD(T) approach provides
a low-cost route toward achieving accurate adsorption energies. This
sets the stage for affordable and reliable theoretical predictions
of chemical reactions on surfaces to guide the realization of new
catalysts and gas storage materials.