Low-temperature dynamical simulation of spin-boson systems.

The dynamics of spin-boson systems at very low temperatures has been studied using a real-time path-integral simulation technique which combines a stochastic Monte Carlo sampling over the quantum fluctuations with an exact treatment of the quasiclassical degrees of freedoms. To a large degree, this special technique circumvents the dynamical sign problem and allows the dynamics to be studied directly up to long real times in a numerically exact manner. This method has been applied to two important problems: (1) crossover from nonadiabatic to adiabatic behavior in electron transfer reactions, (2) the zero-temperature dynamics in the antiferromagnetic Kondo region 1/2 < K < 1 where K is Kondo’s parameter. Typeset using REVTEX ∗Present address: Fakultät für Physik, Universität Freiburg, Hermann–Herder–Str. 3, D-79104 Freiburg, Germany