The electronic structure and photodynamics of DMABN were previously studied quite extensively in Refs. [45,73,81,88-92]. For the LVC model proposed in Ref . [73], it was found that DMABN encounters an "immediate" conical intersection (CI) between states S 1 and S 2 after photoexcitation to S 2 , which is accessible directly by the photoexcited wavepacket located in the FC region. This leads to a fast population transfer from state S 2 to S 1 . Ab initio studies have shown that DMABN has an additional CI between S 2 and S 1 that is associated with a rotation of the dimethylamino group , but the LVC model does not account for this CI.