THE EFFECT OF DENSITY-GRADIENT CORRECTIONS FOR A MOLECULE SURFACE-POTENTIAL ENERGY SURFACE - SLAB CALCULATIONS OF CU(100)C(2X2)-CO

We have performed slab calculations on the periodic adsorption, with a coverage theta = 0.5, of CO on the Cu(100) surface. Using nonlocal co rrections to the local density approximation (LDA), the calculated che misorption energy is 0.7 eV, and the top site is slightly preferred ov er the hollow site. These results are in substantially better agreemen t with the experiment than the LDA results. The structure and vibratio nal frequencies are not much influenced.