What's an energy barrir to rotation? I have data on the enrgy at anti and gauche conformations of 1-iodopropane. I have also graphed the data (steric energy vs dihedral angle) from the graph, do I just subtract the trough at anti from the trough at gauche? so from anti to gauche, it'd be a positive number whereas from gauche to anti would be a negative number?? What about for gauche to gauche? since the energies are the same at the two gauche conformations, would it be 0??