Renormalized energy of ground and first excited state of Fröhlich polaron in the range of weak coupling

Tkach, Seti, Voitsekhivska, Pytiuk
2015 Condensed Matter Physics  
Partial summing of infinite range of diagrams for the two-phonon mass operator of polaron described by Fr\"{o}hlich Hamiltonian is performed using the Feynman-Pines diagram technique. Renormalized spectral parameters of ground and first excited (phonon repeat) polaron state are accurately calculated for a weak electron-phonon coupling at $T=0$ K. It is shown that the stronger electron-phonon interaction shifts the energy of both states into low-energy region of the spectra. The ground state
more » ... he ground state stays stationary and the excited one decays at a bigger coupling constant.
doi:10.5488/cmp.18.33707 fatcat:osj5vcvgl5doljlbylxqe2epyq