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A comparison of density functionals was carried out for systems consisting of a methanethiyl radical adsorbed on gold in different configurations. PW91, PBE, B3LYP and BLYP were tested in a periodic slab approach. Cluster calculations were carried out so as to compare the above mentioned functionals and many others with CR-CCSD (T) and MRMP2 as references. PW91 and PBE provide close results. Energy surfaces calculated by means of PW91, PBE, M06 and TPSSh are in good agreement with the references. M11 performs dissimilarly from M06, in particular it predicts slightly shorter bond lenghts. BLYP gives rather poor results. The semiempirical scheme of Grimme as parameterized in B97-d and the local response dispersion as parameterized in long range corrected BOP-LRD provide very different estimates of the dispersion energy. Unexpectedly rPBE, B3LYP and CAM-B3LYP perform alike and do not match well with the references, though application of a dispersion energy correction in the Grimme scheme, brings them in a much more favorable position.

We present a method that adapts the parameters describing the surface dynamics of an epitaxial system to a set of experimental intensities of He scattering at thermal energies. The method is applied to the problem of Ag growth on a Pt(111) surface at temperatures between 250 and 600 K.

The sudden approximation can be the foundation of a code for performing inexpensive calculations on light particle scattering from huge surface systems. The paper describes the mathematical framework and a sample code which can be used to perform sudden calculations either in the semiclassical approximation or in an exact numerical approach. Also a straightforward extension to the treatment of inelastic collisions in a discrete set of excited states is derived and implemented.

The interaction among Ag adatoms on a Pt(1 1 1) surface was modelled and the resultant thermodynamics simulated on the basis of a Monte Carlo approach. The parameters of the interaction were adjusted so as to yield a reasonable comparison between calculated He diffraction intensity from the obtained samples and experimental data.

Simulated specular scattering intensity of He particles from Xe and CO adsorbed on Pt surfaces shows distinctive features of the surface order parameters which are, however, not observed in experiments. Inferences may be drawn about the influence of long-range order on the scattering properties.