Variational dynamics of the sub-Ohmic spin-boson model on the basis of multiple Davydov D1 states
Date of Issue2016
School of Materials Science and Engineering
Dynamics of the sub-Ohmic spin-boson model is investigated by employing a multitude of the Davydov D1 trial states, also known as the multi-D1Ansatz. Accuracy in dynamics simulations is improved significantly over the single D1Ansatz, especially in the weak system-bath coupling regime. The reliability of the multi-D1Ansatz for various coupling strengths and initial conditions is also systematically examined, with results compared closely with those of the hierarchy equations of motion and the path integral Monte Carlo approaches. In addition, a coherent-incoherent phase crossover in the nonequilibrium dynamics is studied through the multi-D1Ansatz. The phase diagram is obtained with a critical pointsc = 0.4. For sc < s < 1, the coherent-to-incoherent crossover occurs at a certain coupling strength, while the coherent state recurs at a much larger coupling strength. For s < sc, only the coherent phase exists.
The Journal of Chemical Physics
© 2016 American Institute of Physics. This paper was published in Journal of Chemical Physics and is made available as an electronic reprint (preprint) with permission of American Institute of Physics. The published version is available at: [http://dx.doi.org/10.1063/1.4939144]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.