First-principles calculations are a cornerstone of modern surface science and
heterogeneous catalysis. However, accurate reaction energies and barrier
heights are frequently inaccessible due to the approximations demanded by the
large number of atoms. Here we show that these approximations can be
systematically eliminated to solve the many-electron Schr\"odinger equation for
molecules on surfaces with chemical accuracy, commonly defined as 1 kcal/mol.
As a demonstration, we study water on the surface of
Al2βO3β and TiO2β, two prototypical and
industrially important metal oxides for which we obtain converged energies at
the level of coupled-cluster theory with single, double, and perturbative
triple excitations [CCSD(T)], commonly known as the "gold-standard" in
molecular quantum chemistry. We definitively resolve the energetics associated
with water adsorption and dissociation, enabling us to address recent
experiments and to analyze the errors of more commonly used approximate
theories.Comment: 6 pages (w/o SI), 3 figure