The joint probability distribution in (s OH , max{f 0,n }) is depicted in Fig. for the trajectory at T = 370 K. The main feature appears at s OH ≈ 1.0, indicating spin localization and thus hydrogen bonding. That said, the long tail in the distribution of s OH is associated with the largest oscillator strengths in the TD-DFT calculations. Values of s OH and max n {f 0,n } are anti-correlated, with oscillator strengths in the tail of the s OH distribution that are 4-5× larger than those obtained for hydrogen-bonded configurations.