Physics – Condensed Matter – Strongly Correlated Electrons
Scientific paper
2006-10-27
Physics
Condensed Matter
Strongly Correlated Electrons
Accepted for publication (Int.J.Mod.Phys.B) - 13 pages
Scientific paper
10.1142/S0217979207036564
We focus on the definition of the unitary transformation leading to an effective second order Hamiltonian, inside degenerate eigensubspaces of the non-perturbed Hamiltonian. We shall prove, by working out in detail the Su-Schrieffer-Heeger Hamiltonian case, that the presence of degenerate states, including fermions and bosons, which might seemingly pose an obstacle towards the determination of such "Froehlich-transformed" Hamiltonian, in fact does not: we explicitly show how degenerate states may be harmlessly included in the treatment, as they contribute with vanishing matrix elements to the effective Hamiltonian matrix. In such a way, one can use without difficulty the eigenvalues of the effective Hamiltonian to describe the renormalized energies of the real excitations in the interacting system. Our argument applies also to few-body systems where one may not invoke the thermodynamic limit to get rid of the "dangerous" perturbation terms.
Acquarone Marcello
Ventura C. I.
No associations
LandOfFree
Revisiting the Froehlich-type transformation when degenerate states are present does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Revisiting the Froehlich-type transformation when degenerate states are present, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Revisiting the Froehlich-type transformation when degenerate states are present will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-169240