Instability of the marginal commutative model of tunneling centers interacting with a metallic environment: Role of the electronhole symmetry breaking
Abstract
The role of the electronhole symmetry breaking is investigated for a symmetrical commutative twolevel system in a metal using the multiplicative renormalization group in a straightforward way. The role of the symmetries of the model and the pathintegral technique are also discussed in detail. It is shown that the electronhole symmetry breaking may make the model noncommutative and generate the assisted tunneling process which is, however, too small itself to drive the system into the vicinity of the twochannel Kondo fixed point. While these results are in qualitative agreement with those of Moustakas and Fisher [Phys. Rev. B 51, 6908 (1995); 53, 4300 (1996)], the scaling equations turn out to be essentially different. We show that the main reason for this difference is that the procedure for the elimination of the highenergy degrees of freedom used by Moustakas and Fisher leaves only the freeenergy invariant, however, the couplings generated are not connected to the dynamical properties in a straightforward way and should be interpreted with care. These latter results might have important consequences in other cases where the pathintegral technique is used to produce the scaling equations and calculate physical quantities.
 Publication:

Physical Review B
 Pub Date:
 November 1997
 DOI:
 10.1103/PhysRevB.56.12947
 arXiv:
 arXiv:condmat/9706092
 Bibcode:
 1997PhRvB..5612947Z
 Keywords:

 72.10.Fk;
 72.15.Cz;
 71.55.i;
 Scattering by point defects dislocations surfaces and other imperfections;
 Electrical and thermal conduction in amorphous and liquid metals and alloys;
 Impurity and defect levels;
 Condensed Matter  Strongly Correlated Electrons
 EPrint:
 latex, figures in ps file added