Incoherent tunneling surface diffusion

In this work, incoherent tunneling surface diffusion is analyzed by means of the stochastic wave function (SWF) method within the Lindblad formalism. Previous calculations based on the transition state theory (TST) were unable to provide reasonable values of friction coefficients for the diffusion motion of H and D adsorbates on a Pt(111) surface. Thermal activation and tunneling regimes were covered by varying the surface temperature, approaching the so-called cross-over temperature. Numerical results for the total hopping/tunneling rates are fairly good when compared to the experimental values by assuming a simple cosine corrugation function. No fitting has been carried out and estimated values of the physical parameters (friction coefficients, well and barrier frequencies and barrier height), extracted from the thermal activation regime, are used. Finally, survival probabilities on the different wells are also reported.