The C=C bond relaxation pathway from Franck-Condon (FC) to alternate bond-lengths (ABL) in the 13-cis, 15-anti K intermediate of AT-BR (all-trans Bacteriorhodopsin). The CASPT2//CASSCF/MM minimum energy paths (MEPs) of the FCABL in three different conformations of the carboxylic acid group of protonated ASP212, i.e., B OD1s, syn conformation-O1 protonated, C OD2s, syn conformation-O2 protonated and D OD1a, anti conformation-O1 protonated. The values 0.18, 2.97 and 6.45 kcal mol -1 are associated with the energy barriers along the C=C bond relaxation path of OD1s, OD2s, and OD1a, respectively. Source data are provided as a Source Data file.
