A new decoupling approximation has been introduced in the Green's function equation-of-motion analysis of the large polaron. Considering those Feynman diagrams which correspond to the two-phonon Tamm-Dancoff approximations an expression for the polaron ground state energy has been derived. It is fou
Ground state energy of a polaron in a superlattice
โ Scribed by S.Y. Mensah; F.K.A. Allotey; G. Nkrumah; N.G. Mensah
- Publisher
- Elsevier Science
- Year
- 2001
- Tongue
- English
- Weight
- 377 KB
- Volume
- 29
- Category
- Article
- ISSN
- 0749-6036
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โฆ Synopsis
The ground state energy of a polaron in a superlattice was calculated using the double-time Green functions. The effective mass of the polaron along the planes perpendicular to the superlattice axis was also calculated. The dependence of the ground state energy and the effective mass along the planes perpendicular to the superlattice axis on the electron-phonon coupling constant ฮฑ and on the superlattice parameters (i.e. the superlattice period d and the bandwidth ) were studied. It was observed that if an infinite square-well potential is assumed, the ground state energy of the polaron decreases (i.e. becomes more negative) with increasing ฮฑ and d, but increases with increasing . For small values of ฮฑ, the polaron ground state energy varies slowly with , becoming approximately constant for large . The effective mass along the planes perpendicular to the superlattice axis was found to be approximately equal to the mass of an electron for all typical values of ฮฑ, d and .
๐ SIMILAR VOLUMES
Improvements are performed on a recently proposed statistical theory of the mean field of a many-fermion system. The dependence of the predictions of the theory upon its two basic ingredients, namely the Hartree Fock energy and the average energy of the two particle two hole excitations, is explored