In Figure the phase of the transmission of each MO for butane is shown for both the all-trans (θ = 180 • ) and the all-cis (θ = 0 • ) configuration. It is clear that the phase of the MOs of the σ-system only varies slightly when the dihedral angle changes. This minor change is in contrast with π-system where the different electrode positions have a substantial impact on the resulting phase.