THEORETICAL-STUDY OF THE VALENCE LEVEL PHOTOEMISSION SPECTRUM OF C-6 ADSORBED ON NI, PD AND PT METAL-SURFACES

The valence hole spectral functions of C-6, NiC6 PdC6 and PtC6 are cal culated by the ab initio third-order algebraic-diagrammatic-constructi on (ADC(3)) Green function method using an extended basis set. The cal culations for XC6, (X=Ni, Pd, Pt) were performed, assuming the top sit e adsorption of the two ring forms of C-6. These are the benzene struc ture ((1)A(1g)) possessing D-6h symmetry and a distorted cyclic form ( (1)A'(1)) of D-3h symmetry. The changes in spectral features (spectral intensity and energy level separations) from the free molecule to the adsorbate are predicted. The possibility of using the adsorbate data to determine the geometric structure of the adsorbed C-6 molecule is d iscussed. (C) 1997 Elsevier Science B.V.