Abstract: Eighty years ago the Norwegian scientist Egil Hylleraas realized that an amazingly accurate wavefunction for the helium atom could be made by including dependence on the interelectronic distance explicitly. His pivotal calculations showed beyond doubt that Schrödinger formulation of quantum mechanics worked for two-electron as well as one-electron atoms.

Abstract: Scaling relations are presented which have the capability to estimate adsorbate-surface bond energies for hydrogen-containing molecules on transition metal surfaces with reasonable accuracy. The relations provide a method for estimating hydrogenation reaction energies, leading to new possibilities in using electronic structure simulations in the search for new catalysts. Using the selective hydrogenation of acetylene to ethylene as an example, it is shown how the adsorption energy of one single species can be used as a descriptor for the catalytic activity and selectivity.