Since release V6.4 electronic excitation energies can also be computed at the (conventional) CCSD level. For this the data group $excitations has be added (the same keyword as for CC2 apply). The implementation is currently restricted to vertical excitation energies (no transition moments or properties available) and in the closed-shell case to singlett excited states.
Note that for single-excitation dominated transitions CCSD is as CC2 correct
through second-order in H and does not neccessarily more accurate than CC2.
It is, however, for double excitations still correct through first-order, while
CC2 describes double excitations only in a zero-order approximation.
Therefore, CCSD results are more robust with respect to double excitation
contributions to transitions and are thus usefull to check if CC2 is
suitable for a certain problem.