Green’s function methods for open molecular systems.

Abstract
Developments of experimental techniques at the nanoscale require corresponding
developments in theoretical methods. With the focus of experimental research shifting
to open molecular systems, chemical theory must provide techniques capable of
describing the responses of open non-equilibrium quantum systems while accounting
for environmental effects. Moreover, the methods must be consistent (that is, derived
in a way that allows to estimate accuracy of the prediction, rather than being
postulated in the “state-of-the-art” manner), applicable over a wide range of
parameters, capable of describing system’s steady states and transient responses, and
(following longstanding chemical tradition and to connect to electronic-structure

quantum chemistry theory) yield access to the molecular many-body states. Non-
equilibrium Green’s functions (standard NEGF and its many-body flavors) provide a

convenient theoretical tool satisfying the requirements above. I will review our efforts
in the theoretical formulation of optical spectroscopy, non-adiabatic molecular

dynamics, quantum control, and quantum thermodynamics using various non-
equilibrium Green’s function techniques.