Minimum energy conical intersection (MECI) is the low-lying point on the CI hyperseam that facilitates ultrafast radiationless transition in photochromes. Time dependent density functional theory calculations using Maeda's updated branching plane method were employed in the study of indolylfulgides' structure at the MECI. Four criteria were used to effectively characterize the influence of the MECI structure on the photoreactivity of indolylfulgides; three of these criteria (molecular orbital, bond lengths and the height of C-6 trigonal pyramid) were paramount to identifying one novel MECI structure and confirming 2 others previously reported. (C) 2014 Elsevier B. V. All rights reserved.