  Core-electron x-ray photoelectron spectroscopy is a powerful technique for
studying the electronic structure and chemical composition of molecules, solids
and surfaces. However, the interpretation of measured spectra and the
assignment of peaks to atoms in specific chemical environments is often
challenging. Here, we address this problem and introduce a parameter-free
computational approach for calculating absolute core-electron binding energies.
In particular, we demonstrate that accurate absolute binding energies can be
obtained from the total energy difference of the ground state and a state with
an explicit core hole when exchange and correlation effects are described by a
recently developed meta-generalized gradient approximation and relativistic
effects are included even for light elements. We carry out calculations for
molecules, solids and surface species and find excellent agreement with
available experimental measurements. For example, we find a mean absolute error
of only 0.16 eV for a reference set of 103 molecular core-electron binding
energies. The capability to calculate accurate absolute core-electron binding
energies will enable new insights into a wide range of chemical surface
processes that are studied by x-ray photoelectron spectroscopy.
