The local density functional approximation (LDA) has been employed to study the adsorption orientation of benzene molecule on Cu(1 0 0) surface, The results suggest the coverage-dependent change in adsorption geometry from flat to tilted benzene. At low coverage the molecule lies flat, is strongly adsorbed, and is characterized by a relatively low Cp-z binding energy. At high coverage, the molecule is tilted with respect to the metal surface. It was characterized by a relatively high H Is binding energy. Orbital and Mulliken analysis are employed to interpret the mechanism for the phenomenon. The optimized adsorption orientations agree with proposed results from a precious experiment work. (c) 2005 Elsevier B.V. All rights reserved.