Ab-initio static exchange calculations of shake-up spectra of molecules and surface adsorbates

An ab initio approach to core electron shake spectra based on the sudden approximation and on a direct implementation of the static-exchange (STEX) method is reviewed. It employs appropriately spin-coupled two-hole potentials for the various shake-up/shake-off channels and is far extendable in the number of atoms treated, in the dimension of the one-particle basis set and in the spectral range. Using cluster modelling it has been implemented for shake spectra of molecules adsorbed on surfaces, while considering oligomers of increasing size it can be used to model the shake spectra of polymers. Applications of the method to shake spectra of several systems are discussed: CO chemisorbed on Cu(100), H₂CO, C₂H₄, and aniline.