A MIXED-BASIS APPROACH FOR THE EFFICIENT CALCULATION OF POTENTIAL-ENERGY SURFACES

First principles calculations based on density functional theory are h aving an increasing impact on our understanding of molecule-surface in teractions. For example, calculations of the multidimensional potentia l energy surface have provided considerable insight into the dynamics of dissociation processes. However, these calculations, using a plane- wave basis set, are very expensive to compute if they are to be fully converged with respect to the plane-wave energy cut-off, k-point sampl ing, supercell size, slab thickness, etc. Because of this, in this stu dy, we have implemented a mixed-basis approach which uses pseudo-atomi c orbitals and a few low-energy plane waves as the basis set within a density functional, pseudopotential calculation. We show that the meth od offers a computationally cheap but accurate alternative. The energy barrier for hydrogen dissociation on Cu(111) is calculated as an exam ple, (C) 1998 Elsevier Science B.V. All rights reserved.