Computational investigation of the L2,3-edge spectra of bulk and (110) surface of rutile TiO2

The Ti-L2,3 edge spectra of rutile TiO2 have been calculated with the time-dependent density functional theory (TDDFT), employing the zero-order regular approximation (ZORA) at both scalar relativistic and spin\u2013orbit coupling levels. The bulk rutile as well as its (110) surface has been considered with the aim of analyzing the sensitivity of the calculated Ti L2,3 spectra to the different symmetry environments of the Ti atom in the two conditions. A good agreement with the experiment has been obtained in both cases. The inclusion in the theoretical scheme of both the configuration interaction and the spin\u2013orbit coupling is essential to correctly describe the intensity distribution among the L3- and L2-edge transitions. The fine structures of the spectra reflect the symmetry environment of the absorbing Ti atom as well as the long range contribution from neighbor Ti atoms