A quantum chemical investigation of imide adsorption at model Cu(110) surfaces

The adsorption of imide (NH) on small clusters of copper atoms representing a Cu(110) surface has been investigated using density functional methods. The calculations show that the imide adsorbs in the short bridge site with a Cu-N distance of 1.856 Angstrom and an N-H bond length of 1.031 Angstrom. The formation of imide "chains" in the [1 (1) over bar 10] direction gives additional stabilisation where the imide spacing within the chains is 5.1 Angstrom (i.e. two copper lattice spacings). An isolated imide prefers a li near geometry with the N-H bond orientated perpendicular to the surface pla ne but in the chains further stabilisation is obtained if the imides are ti lted alternately in the [100] direction. Despite the relatively small clust er sizes used, the results show very good agreement with experimental resul ts and help elucidate some experimental observations.