A new variational ansatz in the polaron theory

Abstract

Abstract A new translational invariant variational statement is given, which is exact to the order α 2 for weak coupling and which is in the limiting case of strong coupling regarding the polaron self‐energy not poorer as‐0.105 α 2 h ω. In the limiting case of weak coupling the polaron mass, the contributions to the self‐energy due to the individual components of Fröhlich's Hamiltonian, and up to the order α 2 the mean value of virtual phonons in the ground state are exactly calculated.