GROUND-STATE PROPERTIES OF A DISSIPATIVE 2-STATE SYSTEM COUPLED TO PHONONS

We present a systematic analysis of the ground state properties of a t unneling system coupled to an Ohmic bath. The nonadiabatic effects ind uced by coupling with tunneling particle, on the ground state properti es of phonons are taken into account. For this we have considered both displacement and deformation of phonons via a variational treatment. The symmetry breaking transition, or the delocalization-localization t ransition, of the tunneling particle is presented and is compared with earlier known results. We also show that in the critical regime a gap will be opened near the zero momentum in the spectrum of the phonons. The modified phonon spectrum along with the phonon displacement field correlation functions have been calculated. It is shown that in the c ritical regime the tunneling system stabilizes the lattice against lon g wavelength fluctuations.