Away from the transmission resonances, the transmission phase is 0 or ±π so t i = ± √ T i . As the transmission phase is unchanged with dihedral angle changes for butane, Equation 12 can be written in a large energy range around the Fermi level (at least in [-2.0, 2.0]eV) as, (13) where the sign in front of each term is determined by the phase indicated in Figure , '+' for 0 and '-' for ±π. With the change of the dihedral angle from 0 • to 180 • , transmission dips may appear or disappear in the energy range [-2.0, 2.0]eV but the phase of each MO is constant, consequently the transmission dips can only be caused by the change of the width and position of individual MO contributions to the transmission. Conversely, the sign of each term in Equation for the π-system benzene will change depending on the connection to the electrodes giving a different picture of the orbital contributions to interference in this case.