Optimized key geometries (hydrogen bond length and donor–acceptor distance) at reactants PQ (PQ*)-1-min and PQ-2-min, and at products PQ*-1-PT-min and PQ*-2-PT-min.

Bond length (Å)	PQ(PQ*)-1-min		PQ-2-min		PQ*-1-PT-min	PQ*-2-PT-min
	S0	S1	S0	S1	S1	S1
N–H1	2.032	1.860	1.671	—	1.014	1.021
O–H1	0.981	1.006	1.003	—	2.392	1.894
N–O	2.892	2.772	2.583	—	3.057	2.703