Cluster calculation of carbon monoxide on a Cu surface using the self-consistent-field-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>X</mml:mi><mml:mi>α</mml:mi></mml:math>-scattered-wave method

Abstract

Two geometries of CO chemisorbed on a Cu(100) surface have been studied using the self-consistent-field-$X\ensuremath{\alpha}$-scattered-wave method. Both geometries assume the CO molecule is bonded to the Cu surface with the C end down; one geometry is in the fourfold symmetric hole site and one is directly on top of a Cu atom. The calculated valence density of states for the fourfold-symmetry case gives a satisfactory interpretation of the two main peaks below the copper $d$ band in the uv photoemission spectra (UPS). A third weaker peak of the UPS data can be correlated with a CO molecule adsorbed directly on top of a copper atom.