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 vibrat ional properties of CO on Cu(001). We use density functional theory in the local density approximation (DFT-LDA) and Vanderbilt ultrasoft ps eudopotentials. A full structural minimization of the clean Cu(001) su rface, 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 outwa rds by 0.7%, while the others relax inwards by -2.5%. The electronic s tructure and the work function of the relaxed surfaces are presented. Preliminary results for the CO vibrational frequencies are given in th e limit of full coverage.