MOLECULAR-DYNAMICS SIMULATIONS OF NA DEPOSITION ON THE TIO2(110) SURFACE

A computational study of the sodium deposition on the TiO2(110) rutile surface was carried out. Using both molecular dynamics methods and co mplementary ab initio Hartree-Fock embedded cluster calculations, the Na arrangements on the surface for coverages up to theta = 0.5 ML were considered. Our simulations show that Na adsorbs on the surface bindi ng three oxygen atoms, two protruded and one basal, in a quasi-symmetr ic configuration. This coordination type is found whatever the coverag e, in agreement with previous experimental and theoretical works. The Na atoms are found to be arranged in an alternated disposition around the protruded oxygen atom rows. This distribution is almost perfect fo r a theta = 0.25 ML coverage, since coadsorption effects are small and the Na atoms find place enough to be accommodated. For a coverage of theta = 0.5 ML, some islands, in which the Na atoms are facing each ot her across two protruded oxygen atoms, are found, even in long time si mulations, Formation of Na2O dimers was not observed. (C) 1998 Elsevie r Science B.V. All rights reserved.