Yuen-Zhou, JoelTempel, DavidRodríguez-Rosario, César A.Aspuru-Guzik, Alan2011-01-102010Yuen-Zhou, Joel, David Gabriel, César A. Rodríguez-Rosario, and Alán Aspuru-Guzik. 2010. Time-dependent density functional theory for open quantum systems with unitary propagation. Physical Review Letters 104(4): 043001.0031-90071079-71141092-0145http://nrs.harvard.edu/urn-3:HUL.InstRepos:4646394We extend the Runge-Gross theorem for a very general class of open quantum systems under weak assumptions about the nature of the bath and its coupling to the system. We show that for Kohn-Sham (KS) time-dependent density functional theory, it is possible to rigorously include the effects of the environment within a bath functional in the KS potential. A Markovian bath functional inspired by the theory of nonlinear Schrödinger equations is suggested, which can be readily implemented in currently existing real-time codes. Finally, calculations on a helium model system are presented.en-USJournal Article2011-01-1010.1103/PhysRevLett.104.043001