Theoretical studies of energy photoemission spectra (XPS) of S and SO₂ adsorbed on Ni clusters by Hartree-Fock method

Theoretical results of photoemission energy spectral of the atomic sulfur and of the SO₂ molecule, adsorbed over surfaces of Ni(110) and Ni(111) clusters, are reported in this work. Clusters with 11, 13, 15 and 17 atoms of Ni were used for the model. The calculations were done by Hartree-Fock method, and basis sets of type STO-NG and p-q1G (p=3,6; q=2,3; N=3,6) were used. The ionization potentials (IP) were interpreted within the Koopmans Theorem. The results obtained for the IP of 1s, 2s and 2p orbitals are 2472.03 eV, 238.14 eV and 173.55 eV, respectively; while for the same orbitals of the sulfur in SO₂ these values are 2481.30 eV, 246.61 eV and 182.17 eV. The theoretical results were compared with experimental results reported in the references, and the error ranges are between 5 eV and 30 eV, in agreement with the stardard for the Hartree-Fock method.