Theoretical study of NH3 chemisorption on Pt(111)

The chemisorption of NH3 on Pt(111) has been studied utilizing a Pt-10 clus ter model in conjunction with the ab initio Hartree-Fock and the hybrid B3L YP Density Functional Theory based methods. For the on-top chemisorption bo th techniques predict that NH3 chemisorbs molecularly with an equilibrium g eometry representing a small distortion of the gas phase molecular geometry and no azimuthal preference. The interaction energy calculated by means of the two methods appears to be quite close to the experimental estimate, sp ecially for the B3LYP calculated value. The similarity between HF and B3LYP spreads to other electronic structure properties of the chemisorbed molecu le such as the Delta(1e-3a(1)) shift, the net charge transfer from NH3 to t he surface and the bonding mechanism. (C) 1999 Elsevier Science B.V. All ri ghts reserved.