Stationary and dynamical descriptions of strong correlated systems

Abstract

This work is mainly devoted to the description of processes that involve the interaction between an atom and a surface, in which a strong Coulomb repulsion on the atomic site ͑U͒ limits the charge exchange to one electron ͑infinite-U limit͒. In this limit, the Anderson Hamiltonian for a many-fold ͑N͒ of states localized on the atomic site can be represented in terms of auxiliary bosons and physical operators in the mixed bosonelectron space can be defined. In this work the Hamiltonian is solved by defining appropriate Green's functions for physical operators. Then we solved the equations of motion of these Green's functions, up to a second order in the atom-surface coupling, either for the stationary case or for a real time-dependent problem. We show that our approach reproduces the known exact results in the nondegenerate ͑N =1͒ case, and for N ՝ 1 gives excellent agreement with exact calculations and approximations valid for large N ͑the 1 / N expansion͒. Finally, the accurate description of dynamical processes is shown by the comparison with the exact results available for a small four-level system. In this case we also compare with results obtained by using the noncrossing approximation and with the usual spinless model calculation.

Kondo resonance decoherence caused by an external potential

“…Now we turn our attention to the nonequilibrium case V = 0 in the symmetric situation, where the chemical potentials of the left and right leads are ±V /2. A fully consistent solution of the case V = 0 requires the application of the Keldysh formalism, as explained in [19]. The symmetric case can be analyzed, however, at the level of the above equations because, to good accuracy, < n −σ > and <χ † −σĉk−σ > do not vary with V for the values used here.…”

“…Eqs. (12)(13)(14) reproduce the conventional T 2 -approximation of [19] by neglecting all the terms proportional to T 3 . One can get, however, a new (and effective) T 2 -order near the Kondo resonance by neglecting the terms that couple these equations in an integral way.…”

“…(16), < n −σ > and <χ † −σĉk−σ > have to be calculated self-consistently [14], [19]. At zero temperature and in a wide-band approximation, they are given by:…”

Auger neutralization and ionization processes for charge exchange between slow noble gas atoms and solid surfaces

“…6. The rate for RI of 2s 3S is atom-surface potential barrier which has a protaken from theory [37,38] and has not been varied nounced effect on AN rates [18]. Finally we note in the simulation.…”

“…1). Resonant processes, being one-electron ones, have been described abundantly in the literature, practically for any atom/solid combination, using different techniques [8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38].…”