title: Coupling of conduction electrons to two-level systems formed by hydrogen: a scattering approach.
abstract: An effective Hamiltonian for a two-level system (TLS) which could model the interaction between a tunneling proton and the conduction electrons of a metal is investigated in a comparative way. In the conventional first-order Born approximation with plane waves, and for small-distance displacement of the tunneling particle, a simple correlation between the atomic motion and angular momentum change of the scattering electron is deduced. For such a displacement, and within a distorted wave Born approximation for initial and final states, the change in the scattering amplitude is expressed via bounded trigonometric functions of the corresponding difference of scattering phase shifts. The numerical value of this amplitude change is analyzed in the framework of a self-consistent screening description for an impurity embedding in a paramagnetic electron gas. The coupling thus obtained of the tunneling proton to a homogeneous electron gas is too weak to be in the range required for realization of the two-channel Kondo effect.
authors.affiliation: Department of Theoretical Physics, Institute of Physics, Technical University of Budapest, H-1521 Budapest, Hungary. Donostia International Physics Center DIPC, P Manuel de Lardizabal 4, E-20018 San Sebastián, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Nagy
authors.forename: A
authors.initials: A
authors.lastname: Zawadowski