Alternative inclusion of non-iterative ${N}^{7}$ triples corrections is described in
Section 7.8.21. These methods called (dT) and (fT) are of similar
accuracy to other triples corrections. CCSD(dT) and CCSD(fT) are equivalent to
the CR-CCSD(T)${}_{L}$ and CR-CCSD(T)${}_{2}$ methods of Piecuch and coworkers.^{723}

Note: Due to a violation of orbital invariance, the (dT) correction can sometimes lead to spurious results. Therefore, its use is discouraged. Use (fT) instead!