All ESRs are destined to spend some time in another institution (secondments). Specifically, Dario has already spent three weeks last October at Milan University in Prof. Rocco Martinazzo’s group, learning new techniques in quantum chemistry. Now, Dario is spending one month in Milan in order to finish a draft of an article in collaboration between three universities: Leiden, Aarhus, and Milan. This work will contribute to shed light on the formation of molecular hydrogen in the interstellar medium promoted by PAHs. Besides, it will allow achieving one of the important deliverables of the network.