Another branch of development concerns the real-time versions of subsystem TDDFT and time-dependent potential-functional embedding theory . The Pavanello group has demonstrated how to investigate system-bath couplings in the framework of real-time subsystem TDDFT, considering one of the subsystems as an open quantum system and another one as a bath . Based on a decomposition of the linear-response functions, Markovian and non-Markovian effects can be distinguished in this formalism. An implementation employing localized basis functions was presented by De Santis et al. ,