The NOCI-RCMO method uses orthonormal molecular orbitals for each state on each fragment but allows non-orthogonality between orbitals in different states or different fragments. From the non-orthogonal and partly redundant orbitals, a common orbital basis is constructed on each fragment by removing linear dependencies among the orbitals in different states, depending on a cutoff value τ MO for the diagonalized overlap matrix. The common orbital bases on each fragment are then collected together to form a large non-orthogonal MO basis for the cluster. The similarity with the GAS truncation arises at the evaluation of matrix elements which requires several determinant pairs due to the non-orthogonality. Determinants are neglected if their CI-coefficient are smaller than another threshold, τ det . The application of NOCI-RCMO to similar aromatic systems as our benzene stack shows that τ det can become as large as 1 • 10 -6 for fragment distances of 5 Å without affecting the total energy value. Unlike GASSCF, τ det does not a priori exclude higher-order charge-transfer configurations. However, if a system is made of weakly interacting fragments and fragment MOs are utilized, charge-transfer configurations will have (vanishingly) small CI-coefficients, and will be excluded at run time by the chosen τ det threshold. A high value of τ det has then a similar meaning as a low number of allowed interspace excitations in GASSCF.