Strong-coupling theory

B. The Main Mechanism Strong Coupling Theory of Anharmonicity... 

In this section we review what has recently become known about the phonon structure in the point-contact spectra [12]. In order to do this, we should refer to the works where the excess current in point contact is considered in terms of the strong-coupling theory. That was first done in the paper of Omel yanchuk, Beloborod ko and Kulik for ballistic S — c — N point contact [10]. The first derivative of /(IP)-characteristic at T = 0 has the following form in this case ... 

LiF to 6.4 for RbCI, indicating the necessity for the use of strong-coupling theory for a quantitative understanding of the alkali halides. 

Before we finish the discussion on the corrections to the HLA it will be useful to say a few words on classical oscillator dipole theory. Mahan (10) was the first to do a self-consistent strong coupling theory for molecular solids (see also his review paper (11)). In this approximation the molecule is considered as a harmonic oscillator and not as a two-level model. This approach is correct for high-frequency intramolecular optical vibrations. However, Mahan calculated the... 

Fig. 13. Theoretical total neutron cross sections according to the strong coupling theory of Feshbach and Weisskopf.

The particle-hole correlation function In analogy to the weak-coupling limit, the strong coupling theory suggests an appropriate particle-hole (or holon-doublon) correlation function for measuring the particle-hole separation in numerical calculations. Suppose that... 

A. G. Moreira and R. R. Netz, Europhys. Lett., 52, 705 (2000). Strong-Coupling Theory for Counter-Ion Distributions. 

The main objectives of this article are (i) to give an account of the simple theory related to spin-lattice relaxation-rates, in a language that is directed, as far as possible, to the practising chemist rather than to the theoretician (ii) to caution against uncritical use of this simple theory for systems that are strongly coupled, or undergoing anisotropic reorientation, or both (hi) to introduce the pulse n.m.r. experiments that are used to measure spin-lattice relaxation-rates, and to stress the precautions necessary for accurate... 

The nitrogen on ruthenium work is consistent with the observation made on the H/Cl/Au Eley-Rideal chemistry and, taken together, the implications of these two pieces of work are quite profound, suggesting that an accurate theory of surface reactions cannot be constructed without accounting for strong coupling between the reaction coordinate and the metals electron... 

The cornerstone of the strong anharmonic coupling theory relies on the assumption of a modulation of the fast mode frequency by the intermonomer distance. This behavior is correlated by many experimental observations, and it is undoubtly one of the main mechanisms that take place in a hydrogen bond. Because the intermonomer distance is, in the quantum model, represented by the dimensionless position coordinate Q of the slow mode, the effective angular frequency of the fast mode may be written [52,53]... 

There are two kinds of damping that are considered within the strong anharmonic coupling theory the direct and the indirect. In the direct mechanism the excited state of the high-frequency mode relaxes directly toward the medium, whereas in the indirect mechanism it relaxes toward the slow mode to which it is anharmonically coupled, which relaxes in turn toward the medium. 

The pure quantum approach of the strong anharmonic coupling theory performed by Marechal and Witkowski [7] gives the most satisfactorily zeroth-order physical description of weak H-bond IR lineshapes. 

We now come back to the simplest possible nuclear spin system, containing only one kind of nuclei 7, hyperfine-coupled to electron spin S. In the Solomon-Bloembergen-Morgan theory, both spins constitute the spin system with the unperturbed Hamiltonian containing the two Zeeman interactions. The dipole-dipole interaction and the interactions leading to the electron spin relaxation constitute the perturbation, treated by means of the Redfield theory. In this section, we deal with a situation where the electron spin is allowed to be so strongly coupled to the other degrees of freedom that the Redfield treatment of the combined IS spin system is not possible. In Section V, we will be faced with a situation where the electron spin is in... 

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