U-TD-DFT
Using a UKS reference in SCF, the input for U-TD-DFT reads:
$TDDFT IMETHOD 2 ISF 0 ... $END
X-TD-DFT
Using a ROKS reference in SCF, the input for Spin-adapted TD-DFT (X-TD-DFT) can be set in two ways.
One uses U-TD-DFT solver to solve the X-TD-DFT in spin-orbit basis [recommended! for efficiency, since integral-direct algorithm has been implemented]:
$TDDFT IMETHOD 2 ISF 0 ... icorrect 1 itest 1 itrans 1 $END
The option itrans will transform the eigenvector in CV(aa),CV(bb) basis into CV(0) and CV(1) basis.
The other one uses the original spin-adapted TD-DFT solver to solve the X-TD-DFT in spin-tensor basis [This is just for MO-based algorithm, which requires the TRAINT section for integral transformations, and hence not recommended for large applications]:
$TDDFT imethod 3 isf 0 ... itest 1 icorrect 1 $END
These two ways give exactly the same excitation energies. The only different is the representation if "itrans" is not used.