# Dresden 2006 – wissenschaftliches Programm

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# HL: Halbleiterphysik

## HL 57: Theory of electronic structure

### HL 57.7: Vortrag

### Freitag, 31. März 2006, 12:30–12:45, BEY 118

**Path-integral treatment of a translation invariant many-polaron system** — •F. Brosens^{1}, S. N. Klimin^{1,2}, and J. T. Devreese^{1,3} — ^{1}TFVS, Department of Physics, Universiteit Antwerpen, B-2610 Antwerpen, Belgium — ^{2}State University of Moldova, Kishinev, Moldova — ^{3}Department of Semiconductor Physics, TU Eindhoven, NL-5600 MB Eindhoven, The Netherlands

Using an extension of the Jensen-Feynman inequality for systems of identical particles, we derived an upper bound for the ground state energy of a translation invariant system of N interacting polarons, taking into account the Fermi-Dirac statistics of the electrons. The developed approach is valid for arbitrary coupling strength.

For sufficiently large values of the electron-phonon coupling constant and of the Coulomb coupling strength, a stable multipolaron ground state can be formed. The total spin of the system then takes its minimal value. The stability region of the multipolaron state becomes narrower if the number of electrons increases. For a stable multipolaron state, the addition energy exhibits peaks corresponding to closed shells. These features of the addition energy, as well as the total spin as a function of the number of electrons, might be observable experimentally, e.g., by capacitance and magnetization measurements in high-Tc superconductors.

This work was supported by the GOA BOF UA 2000, IUAP, FWO-V projects G.0274.01N, G.0435.03 and the WOG WO.035.04N (Belgium).