Time-Dependent Open-Quantum Approach to Two-Dimensional Electronic Spectroscopy within a GW/BSE Active Space.

In this work, we present a theoretical and computational approach that combines real-time propagation of the electronic wave function, the GW/BSE formalism for the electronic structure of ground and excited states, the theory of open quantum systems, and the phase-cycling method to compute two-dimensional electronic spectra (2DES) of molecular systems under realistic excitation conditions. The advantage of this strategy is that it combines the accuracy of first-principle calculations such as GW/BSE with an explicit description of the employed laser pulses. This allows for better adherence to experimental setups. We apply the proposed methodology to benzene, chlorophyll b, and a benzene-phenol dimer, also including a pure electronic dephasing in the time propagation. The calculated 2DES maps reveal clear signatures of stimulated emission and excited-state absorption, as well as coherence dynamics as a function of the population time, both in the absence and presence of pure dephasing. Comparison with experimental and theoretical published data has been carried out, when available.