  The hopping matrix element $t$ quantifies the quantum-mechanical coupling
between frontier orbitals on a pair of nearby molecules. Convenient and
generally applicable methods to determine $t$ from DFT calculations are
lacking; $t$ can be obtained from coupling-induced energy splittings only if
the interacting molecules are identical and symmetrically placed. We present a
simple approach to determine $t$ from DFT results that relies on measuring
hybridization, projecting hybridized pair orbitals onto constituent frontier
orbitals of the interacting molecules, using spatially discretized
wavefunctions (``cube files'') rather than analytical representations. We
demonstrate the method by exploring how $t$ depends on the identity and
relative placement of typical moieties found in semiconducting polymers.
