Jf. Paul et P. Sautet, COMPARISON OF THE NATURE OF THE HYDROGEN-METAL BOND ON PD(111) AND NI(111) BY A PERIODIC DENSITY-FUNCTIONAL METHOD, Surface science, 356(1-3), 1996, pp. 403-409
The adsorption of H on Pd(111) and Ni(111) has been studied with densi
ty functional calculations, including GGA to compute the exchange and
correlation energies. The surface is described by a two-dimensional sl
ab with a periodic (1x1) adsorption of H atoms. Among the surface site
s, the fee hollow site is found to be the most stable on Pd, while on
nickel, the fee and hcp hollow sites give the same binding energies. T
he adsorption energies corresponding to these sites are -0.27 eV and -
0.49 eV for Pd and Ni, respectively. The energy, as well as the geomet
ry, are in good agreement with experimental data. This study focuses o
n the electronic properties of the M-H bond in order to explain the di
fferences that appear between the two metals. The existence of a split
-off state is proven in the case of Pd, and rejected for Ni. A detaile
d investigation of the DOS and COOP curves explains the nature of the
most stable site. It pinpoints the respective roles played by the d an
d sp bands in the adsorption phenomenon.