Manian and co-workers used the ShaMan model, and the continuum energy condition (Equations 49 and 61), focusing on S 1 → S 0 transitions, and found that at the Franck-Condon limit, the rate constants for anthracene, tetracene, and pentacene, were small to negligible. However, contributions due to Herzberg-Teller effects increased the rate constants significantly (Table ). In the case of the polyacenes, second order contributions are observed to dominate internal conversion processes, while for di-keto pyrrolopyrrole and perylene diimide, their contributions are much smaller. Comparing to the Valiev-Plotnikov-Robinson-Bixon-Jortner method, corresponding rate constants were artificially raised due differences between the continuous maximum rather than the discrete maximum.