Ab InitioCalculation of Coverage-Dependent Adsorption Properties of H on Pd(001)

Abstract

The preferential adsorption sites, bond lengths, and vibration frequencies for H on the Pd (001) surface are determined by use of the ab initio pseudopotential local-orbital method. From the calculated total energies we derive a coverage-dependent absorption energy in very good agreement with experiment. We establish that at low coverages ($\theta \le 1$), H occupies fourfold hollow sites. At higher coverages ($1<\mathrm{}\theta \le 2$), islands of bridge-bonded H (local coverage $\theta =2\mathrm{}$) are predicted to coexist with regions of H in hollow sites.