resulting in the N 6 scaling of the method ( T is usually truncated at the same excitation level). The approximations used within the EOM-CC framework preserve a number of important properties, such as orbital invariance with respect to the rotations in the occupied or virtual spaces and size consistency (or size-intesivity). The accuracy of EOM-SF can be systematically improved (up to the FCI limit) by including higher excitations. The benchmarks illustrate that even the lowest-level of EOM-SF methods yield accurate energy gaps due to the built-in balanced treatment of multiple electronic states. For example, when applied for calculating singlet and triplet states in diradicals, EOM-SF-CCSD provides excitation energies with the error bar of 0.03-0.05 eV ; the benchmark study on dicopper SMMs have shown that even very small energy gaps of several hundreds of wave numbers can be resolved.