Sulphur overlayers on Ir(100) and its effect on the adsorption of CO: a DFT study S.H. Ma, Z.Y. Jiao, X.Q. Dai and Z.X. Yang Eur. Phys. J. B, 83 4 (2011) 437-443 Published online: 24 October 2011 DOI: 10.1140/epjb/e2011-20404-7