Calculations of scanning tunneling microscope images of xylene on Rh(111)

We performed a comparative study of scanning tunneling microscope (STM) ima ges of three different isomers of xylene [(CH3)(2)C6H4] adsorbed on Rh(lll) using a computational method based on extended Huckel molecular orbital th eory (EHT). We calculated images for both the isolated molecules and for mo lecules chemisorbed on a rhodium cluster. The intramolecular structure of c alculated images agreed well with previous experimental results. The calcul ated images exhibit a dependence on neither the binding site nor the molecu lar orientation on the surface. No difference was observed between the calc ulated images of occupied and unoccupied states. (C) 2000 Elsevier Science B.V. All rights reserved.