Long-range interactions are missing in the extended Hückel-type (zeroth-order) Hamiltonian H 0 due to its exponential decay with the (diatomic frame scaled) atomic orbital overlap S sc (see the Supporting Information (SI) for details). To avoid the self-consistent solution of equation 2 necessary with an explicitly charge-dependent SQM Hamiltonian, H 1 * uses a newly defined purely geometry-dependent approximation for the local atomic charges q loc .