DFT Calculations as a Tool to Analyse Quadrupole Splittings of Spin   Crossover Fe(II) complexes
  Density functional methods have been applied to calculate the quadrupole splitting of a series of iron(II) spin crossover complexes. Experimental and calculated values are in reasonable agreement. In one case spin-orbit coupling is necessary to explain the very small quadrupole splitting value of 0.77 mm/s at 293 K for a high-spin isomer. 
Juliusz Adam Wolny, Hauke Paulsen, Heiner Winkler, Alfred Xaver   Trautwein and Jean-Pierre Tuchagues
physics.chem-ph