Alternative inclusion of non-iterative triples corrections is described in
Section 7.10.26. 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) and CR-CCSD(T) methods of Piecuch and coworkers.
J. Chem. Phys.
(2005), 123, pp. 224105.
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!