The bonding of benzene-1,4-dithiol to a Au(1 1 1) surface is studied using a Au-25-SC6H4SH model. We find that the most favorable structure has the S directly above an An atom, i.e., an on-top site. If the molecule is constrained to be perpendicular to the surface, the on-top site is the least favorable site and the threefold hollow is the most favorable one. (C) 2002 Elsevier Science B.V. All rights reserved.