Ab initio study of the structural and electronic properties of adsorbates: Co on Cu(001)

We present an ab initio study of the structural, electronic and vibrational properties of CO on Cu(001). We use density functional theory in the local density approximation (DFT-LDA) and Vanderbilt ultrasoft pseudopotentials. A full structural minimization of the clean Cu(001) surface, of the 1 x 1 and c(2 x 2) CO covered surfaces is performed. The first layer of the clean surface relaxes inwards by -3.1%, while the first Cu layer of the 1 x 1 CO covered surface relaxes outwards by +0.5%. On the c(2 x 2) surface the Cu atoms directly under CO relax outwards by 0.7%, while the others relax inwards by -2.5%. The electronic structure and the work function of the relaxed surfaces are presented. Preliminary results for the CO vibrational frequencies are given in the limit of full coverage.