A new tutorial is available to calculate inter-exciton transient absorption by post-processing the Bethe–Salpeter equation (BSE) results with Lumen. The method allows us to compute the transient absorption associated with transitions between excitons. In particular, the initial state can be either a selected excitonic state or a thermal distribution of excitons, including dark excitons with finite center-of-mass momentum.
This approach provides a way to investigate inter-exciton transient absorption without explicitly performing real-time pump–probe simulation.
Turorial: https://www.lumen-code.org/wiki/index.php?title=Inter/Intra_exciton_transitions_from_BSE_post_processing
Reference: Dark exciton signatures in the infrared transient absorption of MoS2 monolayer
