Nonadiabatic Effect and Dynamic Compensation in a Spin-Boson System

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1. Dynamics compensation theory has been proposed for a spin-boson system with a bilinear coupling between. Contributions from the zero-point and thermodynamic fluctuations are completely compensated by those from the dynamical fluctueltions of cohererly excited bosons in the infrared range of boson energy. We have to treat the adiabatic and nonadiababatic effects of the bosonic bath simultaneously. Those are inseparable ones from one another.2. The ground stale has been formulated and studied variationally. This theory describes that in the ohmic case the tunneling-localization transition takes place at a critical coupling strength alpha_c = 1/2 in the white bath ffidt, which is different from 1 obtained by the adiabatic renormalization.3. The thermodynamics and dynamics have been formulated. It has been found that the spin-boson interaction is exhausted by the ground state correlation.4. A new method has been proposed to compute the thermal average by differential operation. On using this method we study the mechanics and next calculate the thermodynamic effect.5. It has been shown that the dynamic compensation is a new concept of renormalization in a system with degenerate potentialftminima(quantum tunneling system)which is coupled to a bosonic bath by a bilinear interaction.