Real time cumulant approach for charge transfer satellites in x-ray   photoemission spectra
  X-ray photoemission spectra generally exhibit satellite features in addition to the quasi-particle peaks due to many-body excitations, which have been of considerable theoretical and experimental interest. However, the satellites attributed to charge-transfer (CT) excitations in correlated materials have proved difficult to calculate from first principles. Here we report a real-time, real-space approach for such calculations based on a cumulant representation of the core-hole Green's function and time-dependent density functional theory. This approach also yields an interpretation of CT satellites in terms of a complex oscillatory, transient response to a suddenly created core hole. Illustrative results for TiO$_2$ and NiO are in good agreement with experiment. 
J. J. Kas, F. D. Vila, J. J. Rehr, and S. A. Chambers
cond-mat.str-el cond-mat.mtrl-sci