First-principles calculations of step formation energies and step   interactions on TiN(001)
  We study the formation energies and repulsive interactions of monatomic steps on the TiN(001) surface, using density functional total-energy calculations. The calculated formation energy of [100] oriented steps agree well with recently reported experimental values; these steps are shown to have a rumpled structure, with the Ti atoms undergoing larger displacements than the N atoms. For steps that are parallel to [110], our calculations predict a nitrogen (N) termination, as the corresponding formation energy is several hundred meV/\AA \ smaller than that of Ti-terminated steps. 
C. V. Ciobanu (Brown U., CSM), D. T. Tambe (Brown U.) and V. B. Shenoy   (Brown U.)