An Improvement of the Feynman Action in the Theory of Polaron. II

Abstract

An improvement of the Feynman action is made by introducing two additional parameters to Feynman’s original theory of polaron. Better upper bounds to the polaron ground state energy than those of Feynman are obtained for α≤5 by the improved trial action. Present numerical calculation gives lower variational energies than have been obtained heretofore for 3.5≤α≤5. An interpolation formula of the polaron mass
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is proposed. Rigid lattice band masses of the electron in several of the alkali and silver halides are obtained by this interpolation formula with the aid of the measured cold polaron mass.