To ascertain the role of the LEF on the initiation of the hydroxylation via an electron transfer from Tetralin to Cpd I, we removed the cage and methyl substitutions of the HM1 from the optimized RC complex to mimic a zero-field environment. Thereafter, we performed a single-point calculation of the RC and its singly occupied SNOs for the reactant geometry (see SI for Mulliken spin density and charges, Table ). Our calculations revealed that in the absence of the LEF, HM1 retains is electrons and so does the substrate TLN (see Figure ). As such, ET does not occur in the absence of the LEF of the cage. We then applied an external electric field (EEF) of similar magnitude as the LEF exerted by the cage and substituted HM1 (the original RC).