Cluster Dynamical Mean-field calculations for TiOCl
  Based on a combination of cluster dynamical mean field theory (DMFT) and density functional calculations, we calculated the angle-integrated spectral density in the layered $s=1/2$ quantum magnet TiOCl. The agreement with recent photoemission and oxygen K-edge X-ray absorption spectroscopy experiments is found to be good. Th e improvement achieved with this calculation with respect to previous single-site DMFT calculations is an indication of the correlated nature and low-dimensionality of TiOCl. 
T. Saha-Dasgupta, A. Lichtenstein, M. Hoinkis, S. Glawion, M. Sing, R.   Claessen, R. Valenti