@tschumpr I’m sorry this reply is so late to the party, but I have to caution you against applying F-/ISAPT to study interactions with epoxides for the same reasons that I cautioned another user against using atomic fragments in this post; especially since you’re breaking two bonds to the same atom (even though they’re both sigma bonds), the charge assignment issues get magnified drastically and make the results unreliable and unpredictable.