The direct interactions between molecule m and n are covered by the zeroth order term, J pq mn (0) , whereas the second term (J pq mn ) accounts for the response of the polarizable environment. Both the zeroth and the first order terms of J pq mn involve the transition densities of molecule m and n. In this work we choose to evaluate J pq mn using a set of atomic partial charges fitted to reproduce the electrostatic potential of the transition density with a constraint to reproduce the transition dipole moment of the excitation. This atomic partial charge method is found to be highly efficient with respect to accuracy and computational costs. Within this point charge representation of the transition density potential the first term of eq 8 becomes 22