Simple Models for Atom-Surface Scattering

The Redfield theory is based on a weak coupling assumption and has been used extensively in nuclear magnetic resonance (NMR) theory for treating the influence of the surroundings on the spectra. Attempts to go beyond the weak coupling limit assumed in the Redfield theory have been made [78], and the requirement of complete positiveness assumed by Lindblad in the coupling between the subsystem and the reservoir has been challenged by Pechukas [79]. 

The dynamics of the system is irreversible in time, both in the Redfield and the Lindblad formalism. This irreversibility arises from the loss of phase information when averaging over the bath system. 

QUANTUM TREATMENT OF ATOM/MOLECULE-SURFACE SCATTERING 

Various other simple semiclassical models both for atom- and molecule-surface diffraction and energy transfer have been proposed by Miller and co workers [51] 

Assuming a trajectory z(t) for the motion toward the surface, it is possible [75,51] to derive a simple expression for the diffraction probabilities, i.e., for scattering from channel (nomo) to (n, m) we have 

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