Integral-functional representation of mass operator of quasiparticles interacting with polarizational phonons at T = 0 K

N. V. Tkach

N. V. Tkach

Qern vec~ki nac onal~ni un versitet, vul.Kocbins~kogo, 2, Qern vc , 274012, UkraÝna (Otrimano 31 lipn 2001 r.; v ostatoqnomu vigld | 18 grudn 2001 r.) Uperxe otrimano nteral~no-funkc onal~ne zobraenn masovogo operatora bezsp novih kvaz qastinok, wo vza mod t~ z polrizac nimi fononami pri T = 0 K. Ce zobraenn ekv valentne bezmenomu rozgaluenomu nteral~nomu drobov .Vono ne zaleit~v d sili zv'zku efektivno vrahovu bagatofononn procesi.

N. V. Tkach, Julia O. Seti, Оxana Voitsekhivska +1 more

Tkach, Seti, Voitsekhivska +1 more

The theory of renormalized energy spectrum of a multi-level quasiparticle interacting with polarization phonons at $T=0$ K is developed within the Feynman-Pines diagram technique in a new approach. It permits a successive separation of multiplicative diagrams from non-multiplicative ones for all orders of mass operator, and their partial summing as well. The obtained mass operator is presented as a sum of branched chain fractions, which effectively take into account the multi-phonon processes. For the two-level quasiparticle it is shown that just the interlevel (non-diagonal) interaction with phonons fundamentally changes the properties of the spectrum. In the vicinity of all threshold energies, the quasi-equidistant phonon satellite bands (i.e., groups of energy levels) are formed. They correspond to the complexes of bound states of a quasi-particle with many phonons.

Zhou Li, Carl J. Chandler, F. Marsiglio

We use both a perturbative Green's function analysis and standard perturbative quantum mechanics to calculate the decrease in energy and the effective mass for an electron interacting with acoustic phonons. The interaction is between the difference in lattice displacements for neighboring ions and the hopping amplitude for an electron between those two sites. The calculations are performed in one, two, and three dimensions, and comparisons are made with results from other electron-phonon models. We also compute the spectral function and quasiparticle residue, as a function of characteristic phonon frequency. There are strong indications that this model is always polaronic on one dimension, where an unusual relation between the effective mass and the quasiparticle residue is also found.

N. V. Tkach, N. V. Lopushanskaya, A. D. Val'