From this analysis we establish a simple rule of thumb that derives from the WH rules to predict the photoswitching ability of a molecule. The process is to inspect the FMOs and find the ones that have the correct π and π*-type character leading to photocyclization. If a lowlying optically bright excited state corresponds to this MO transition, then the compound is likely to photoswitch to the closed form with the correct excitation. Note that while other factors may influence the viability of the photoswitching in practice, the rule of thumb provides an initial prediction on the likelihood of the reaction, and does not provide any information related to the kinetics of the process.