Here, ϵ = 0eV are the on-site energies, with the primary integrals τ prim = -3.5eV, the geminal integrals τ gem = -1.1eV, and the vicinal integrals τ vic = 0.11 -0.7 cos θ where θ is the dihedral angle. For θ = 180 • , butane is in an all-trans configuration and for θ = 0 • it is in a cis-configuration. Using the model Hamiltonian of Equation 1, the transmission can be calculated as