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Green's function theory of the polaron energy‐momentum relation
Author(s) -
von Baltz R.
Publication year - 1972
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220500131
Subject(s) - polaron , physics , excited state , phonon , momentum (technical analysis) , excitation , quantum electrodynamics , singularity , energy–momentum relation , function (biology) , condensed matter physics , quantum mechanics , mathematics , mathematical analysis , electron , finance , evolutionary biology , economics , biology
The energy E ( p ) of a polaron is studied as a function of temperature and momentum p with particular attention focused on the region where the excitation energy E ( p ) – E (0) closely approaches the energy of a longitudinal optical phonon. It is shown that in this region a quasi‐particle description is not adequate, e.g., the horizontal tangent in E ( p ) does not give rise to a singularity in the density of electronic states. The shape of the spectral weight function indicates that even for small coupling strength there is an internal excited state of the polaron.