Elementary arguments that the Wu-Austin Hamiltonian has no finite ground state (the search for a microscopic foundation of Frohlichs theory)

The Wu-Austin Hamiltonian as the basis for deriving Frohlichs rate equation s from a microscopical point of view has been investigated. In addition to an earlier paper we show in a very easy manner that this or similar Hamilto nians have no lower bound and are therefore unphysical. The perturbation ex pansion which is the tool to derive Frohlichs rate equations with this Hami ltonian is not converging. Therefore, the usual derivation of this rate equ ation is not valid. (C) 1999 Elsevier Science S.A. All rights reserved.