Werther, Michael Max Planck Institute for the Physics of Complex Systems, Max Planck Society;
http://iopscience.iop.org/article/10.1088/1402-4896/aac7f9/meta (Publisher version)
Werther, M., & Grossmann, F. (2018). The Davydov D1.5 Ansatz for the quantum Rabi model. Physica Scripta, 93(7): 074001. doi:10.1088/1402-4896/aac7f9.